# Domestic solar panels



## Alcalaina

We’ve just signed up with a local company to install photovoltaic panels on our roof. Apart from reducing our carbon footprint, if electricity prices stay at current rates we should break even in around 8 years. 

We will stay connected to the grid and I understand there is some compensation from suppliers for surplus energy going back into the grid, but the amounts are negligible.

I’d be interested to hear from anyone else who’s done this and whether it has lived up to expectations.


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## kaipa

A good idea but of course like many of these things it requires a long term commitment to give it economic value. Really the government should be giving grants to encourage more people to do the same. Unfortunately, Spain is so heavily influenced by it's big business and the protectionism ( euphemism for corruption) that follows its impossible for more progressive political parties to get through legislation to allow this. The UK does much better at it as public pressure and media are firmly behind such ventures. Here in Spain it is always business as usual!!! Great shame. Still it is good to see individuals taken up the initiative and hopefully more will follow.


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## Alcalaina

kaipa said:


> A good idea but of course like many of these things it requires a long term commitment to give it economic value. Really the government should be giving grants to encourage more people to do the same. Unfortunately, Spain is so heavily influenced by it's big business and the protectionism ( euphemism for corruption) that follows its impossible for more progressive political parties to get through legislation to allow this. The UK does much better at it as public pressure and media are firmly behind such ventures. Here in Spain it is always business as usual!!! Great shame. Still it is good to see individuals taken up the initiative and hopefully more will follow.


There are grants in many ACs, including Andalucia. Since this government abolished the ridiculous "sun tax" in 2019 it's all become a whole lot easier.


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## Megsmum

Grants here too... Can't comment on your solar, we are solar dependant, 7 years ago we installed a system and unlike the ridiculous figures quoted on here and other forums, where I was told upwards of £20k, we paid under 5K and run this house no differently to the one on the UK, with all modern amenities including two freezers with no issues at all. When we have a run of bad weather we charge with the generator for an hour twice a day. Does make you aware of how much power you waste.


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## Jamglish

Megsmum said:


> Grants here too... Can't comment on your solar, we are solar dependant, 7 years ago we installed a system and unlike the ridiculous figures quoted on here and other forums, where I was told upwards of £20k, we paid under 5K and run this house no differently to the one on the UK, with all modern amenities including two freezers with no issues at all. When we have a run of bad weather we charge with the generator for an hour twice a day. Does make you aware of how much power you waste.





Alcalaina said:


> We’ve just signed up with a local company to install photovoltaic panels on our roof. Apart from reducing our carbon footprint, if electricity prices stay at current rates we should break even in around 8 years.
> 
> We will stay connected to the grid and I understand there is some compensation from suppliers for surplus energy going back into the grid, but the amounts are negligible.
> 
> I’d be interested to hear from anyone else who’s done this and whether it has lived up to expectations.


We have also just installed solar panels and have 2.7 kW peak power capacity. An app constantly monitors how much energy we are consuming and how much of that comes from the panels and how much excess goes back to grid. It has only been 2 full days, but they were sunny days. We produce power from about 11 am to 4pm, and yesterday for example we had 8.5 kW-hours generated. I think that the credit received for what goes back to the grid is 5-6 centavos per kW-hour, which is less than the cost to buy the same power even during the cheapest time band. So, I suppose the maximum benefit will come from using power hungry devices ( air conditioning, heating, etc.) during the middle of the day as long as the sun is shining. This is also the time band when energy is the most expensive to buy. So, it will require a shift in energy use patterns compared to before the panels were installed. I will keep track of it and update the story. Meanwhile, I am obsessively staring at the app and watching for clouds!


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## Alcalaina

Megsmum said:


> Grants here too... Can't comment on your solar, we are solar dependant, 7 years ago we installed a system and unlike the ridiculous figures quoted on here and other forums, where I was told upwards of £20k, we paid under 5K and run this house no differently to the one on the UK, with all modern amenities including two freezers with no issues at all. When we have a run of bad weather we charge with the generator for an hour twice a day. Does make you aware of how much power you waste.


Have you thought about storing your surplus in a battery? I gather these are getting cheaper too. Then you might not need the generator!


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## Megsmum

Alcalaina said:


> Have you thought about storing your surplus in a battery? I gather these are getting cheaper too. Then you might not need the generator!


We have 12 batteries. I've not heard of long term storage in a battery.


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## Alcalaina

Megsmum said:


> We have 12 batteries. I've not heard of long term storage in a battery.








solar battery storage


Discover everything you need to know about how to store the energy that your solar panels create with a home battery.




www.edfenergy.com




I don’t know much about them, I just keep seeing them advertised. What do your batteries do then?


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## Megsmum

Alcalaina said:


> solar battery storage
> 
> 
> Discover everything you need to know about how to store the energy that your solar panels create with a home battery.
> 
> 
> 
> 
> www.edfenergy.com
> 
> 
> 
> 
> I don’t know much about them, I just keep seeing them advertised. What do your batteries do then?


They store electricity but when full will only last three/ four days if no sun. I don't know of anyone living off grid who is solar dependant, that doesn't run a generator in winter months. Ours comes on when batteries drop below a certain level. Others just check levels. I know of some who think you can store batteries from summer for the winter, it doesn't work that way.


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## Jamglish

Megsmum said:


> They store electricity but when full will only last three/ four days if no sun. I don't know of anyone living off grid who is solar dependant, that doesn't run a generator in winter months. Ours comes on when batteries drop below a certain level. Others just check levels. I know of some who think you can store batteries from summer for the winter, it doesn't work that way.


Unfortunately, battery storage is currently too expensive. Hopefully that will change in the coming years, along with the cost of electric cars, as both need large capacity batteries. Having sufficient battery storage to last for a few days of cloudy weather would greatly increase the break even point for solar power. You might also need a larger solar panel array to charge the batteries in addition to the power you are already consuming. But sending excess solar power back to the grid and getting credited for it, even though at a cheap rate, seems to be the most cost effective option right now, with a payback period of just a few years. The payback period might also get shorter as electricity costs rise and the cost of the solar array decreases. In addition, having solar water heating is a no-brainer as it is low tech and reduces the considerable energy required to heat water. And, the Costa del Sol is probably one of the best places to install solar power because of the large number of sunny days per year. 
A quick update on my new system: It has now been running for 3 days since installation. It has generated 24 kW-hours, of which I directly used 5.6 kW-hours. The balance went to the grid. During this same time my total consumption was 14 kW-hours. So, I still needed to buy power from the grid in excess of the 5.6 that I directly used, and some of the cost of that will be offset by the power I sent back to the grid. It will be interesting to see the eventual monthly bill for the energy that I bought offset by what I sold.


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## snikpoh

I've been trying to do this for a while now - friend says the rules where we live are that we can't have them as it's a protected area.

I want autoconsumo as it's so hard to het any pay back and batteries are still too expensive. My current quotes show a pay-back period of 4-5 years


Got a quote and all seemed good until I pushed them to get a licence/approval from the town hall. Whilst they have said it is possible, the panels they insist upon (anti glare, bird safe etc.) are simply not available in Spain (or so it seems).

I have now been told that when (if) they do become available, the quote will be 20-30% higher!

What was their point of the original quote if they won't hold to it (nothing in the small print about town hall etc.)?

Also, why are the town halls making it so hard to go green / eco-friendly?


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## Megsmum

Jamglish said:


> Unfortunately, battery storage is currently too expensive. Hopefully that will change in the coming years, along with the cost of electric cars, as both need large capacity batteries. Having sufficient battery storage to last for a few days of cloudy weather would greatly increase the break even point for solar power. You might also need a larger solar panel array to charge the batteries in addition to the power you are already consuming. But sending excess solar power back to the grid and getting credited for it, even though at a cheap rate, seems to be the most cost effective option right now, with a payback period of just a few years. The payback period might also get shorter as electricity costs rise and the cost of the solar array decreases. In addition, having solar water heating is a no-brainer as it is low tech and reduces the considerable energy required to heat water. And, the Costa del Sol is probably one of the best places to install solar power because of the large number of sunny days per year.
> A quick update on my new system: It has now been running for 3 days since installation. It has generated 24 kW-hours, of which I directly used 5.6 kW-hours. The balance went to the grid. During this same time my total consumption was 14 kW-hours. So, I still needed to buy power from the grid in excess of the 5.6 that I directly used, and some of the cost of that will be offset by the power I sent back to the grid. It will be interesting to see the eventual monthly bill for the energy that I bought offset by what I sold.


I think you are referring to Alacainia post. I'm totally off grid. Off grid living and attached to grid totally different. We are already €€€up on our investment seven plus years ago. The prospect of having power bills fill me with dread. We built into our contingency funds upgrade of our system


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## tardigrade

What kind of batteries are you using? AMG Gel?

Tesla's "powerwall" uses lithium which will last a lot longer though it does not seem to be available in Spain thru their european website.. A bigger investment upfront but no dread from power bills or having no electricity for days if something fails.

Have you had to replace any of your system? Inverter? Charge controller?? That will decrease your €€€ ROI over the long run.



Megsmum said:


> I think you are referring to Alacainia post. I'm totally off grid. Off grid living and attached to grid totally different. We are already €€€up on our investment seven plus years ago. The prospect of having power bills fill me with dread. We built into our contingency funds upgrade of our system


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## xgarb

Batteries are still not economically viable if you can grid-tie. My brother-in-law just put in a solar system and he can 'inject' electricity into anyone else's system within a certain distance of his substation. During the day his wife works opposite their house so she will be able to use the 'same' electricity as they are using in the house.

One thing to note.. if you want solar because your supply is intermittent and you grid tie, the solar system will shut off when the supply is cut to protect the electricity company workers.


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## Alcalaina

snikpoh said:


> I've been trying to do this for a while now - friend says the rules where we live are that we can't have them as it's a protected area.
> 
> I want autoconsumo as it's so hard to het any pay back and batteries are still too expensive. My current quotes show a pay-back period of 4-5 years
> 
> 
> Got a quote and all seemed good until I pushed them to get a licence/approval from the town hall. Whilst they have said it is possible, the panels they insist upon (anti glare, bird safe etc.) are simply not available in Spain (or so it seems).
> 
> I have now been told that when (if) they do become available, the quote will be 20-30% higher!
> 
> What was their point of the original quote if they won't hold to it (nothing in the small print about town hall etc.)?
> 
> Also, why are the town halls making it so hard to go green / eco-friendly?


How long ago was this? Things have changed a lot since 2019.


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## tardigrade

The Valencia region also just made it easier to install panels - either in the city or the campo..









Valencia city council set to simplify solar panel installation process to help residents save up to 40% on electricity bills


Valencia city council set to simplify solar panel installation process to help residents save up to 40% on electricity bills. Read this and thousands of other news stories and articles on thinkSPAIN, the leading English language website for Spain.




www.thinkspain.com













High electricity price in Spain sees installation of solar panels double in Valencia


As the electricity price in Spain rises, so the installation of solar panels for own use in the Valencia region is doubling.




inspain.news


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## Max Rigger

IIRC anti-glare panels work better than standard finish, they absorb more light when the sun in lower on the horizon. Bird proof/safe, would that be the meshing you run under panels to stop birds potentially getting stuck?


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## snikpoh

Alcalaina said:


> How long ago was this? Things have changed a lot since 2019.


Last week


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## snikpoh

tardigrade said:


> The Valencia region also just made it easier to install panels - either in the city or the campo..
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Valencia city council set to simplify solar panel installation process to help residents save up to 40% on electricity bills
> 
> 
> Valencia city council set to simplify solar panel installation process to help residents save up to 40% on electricity bills. Read this and thousands of other news stories and articles on thinkSPAIN, the leading English language website for Spain.
> 
> 
> 
> 
> www.thinkspain.com
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> High electricity price in Spain sees installation of solar panels double in Valencia
> 
> 
> As the electricity price in Spain rises, so the installation of solar panels for own use in the Valencia region is doubling.
> 
> 
> 
> 
> inspain.news



I wish that were true - I quoted this to them and they laughed stating their own regulations!


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## xgarb

I can see the argument against panels on the roof tops in pretty villages and protected areas.

Maybe the ayuntamientos could have a little bit of imagination and find some land or roof tops outside of the villages or hidden by trees and let people have solar allotments where instead of growing vegetables, they grow solar energy. You could have your own junction box that measures how much you are adding to the grid and this could then be removed from your bill. You could connect as many panels as you can fit on your plot.

There are associations doing similar things in Spain now. On a larger scale there is this: https://www.pv-tech.org/spains-firs...s-to-provide-energy-bill-savings-of-up-to-30/


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## tardigrade

xgarb said:


> I can see the argument against panels on the roof tops in pretty villages and protected areas.
> 
> Maybe the ayuntamientos could have a little bit of imagination and find some land or roof tops outside of the villages or hidden by trees and let people have solar allotments where instead of growing vegetables, they grow solar energy. You could have your own junction box that measures how much you are adding to the grid and this could then be removed from your bill. You could connect as many panels as you can fit on your plot.
> 
> There are associations doing similar things in Spain now. On a larger scale there is this: https://www.pv-tech.org/spains-firs...s-to-provide-energy-bill-savings-of-up-to-30/


They tried that near Algimia (close to Sagunt) and within 1 week they were all stolen..


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## Alcalaina

xgarb said:


> I can see the argument against panels on the roof tops in pretty villages and protected areas.
> 
> Maybe the ayuntamientos could have a little bit of imagination and find some land or roof tops outside of the villages or hidden by trees and let people have solar allotments where instead of growing vegetables, they grow solar energy. You could have your own junction box that measures how much you are adding to the grid and this could then be removed from your bill. You could connect as many panels as you can fit on your plot.
> 
> There are associations doing similar things in Spain now. On a larger scale there is this: https://www.pv-tech.org/spains-firs...s-to-provide-energy-bill-savings-of-up-to-30/


Nice idea but even vegetables get stolen from allotments so I doubt expensive equipment like this would last long!


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## Max Rigger

I'm not sure how long a village being 'pretty' will stop solar deployment happening, 'we' need the power. I went down to Brecon and there are literally over 100 windturbines there which for me ruin the panorama but...when needs must and all that. If we'd been sensible twenty years ago the UK would have gone over to nuclear power by now.


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## snikpoh

Max Rigger said:


> I'm not sure how long a village being 'pretty' will stop solar deployment happening, 'we' need the power. I went down to Brecon and there are literally over 100 windturbines there which for me ruin the panorama but...when needs must and all that. If we'd been sensible twenty years ago the UK would have gone over to nuclear power by now.


Completely off topic but whilst nuclear might be cheap now, the lasting costs of having to dispose of spent fuel rods is enormous - another problem for our children to deal with!!!


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## tardigrade

snikpoh said:


> Completely off topic but whilst nuclear might be cheap now, the lasting costs of having to dispose of spent fuel rods is enormous - another problem for our children to deal with!!!


In the future with "green" spaceflight and technology ( a space ladder); spent fuel rods will not be a problem.. They will be jettisoned into space and out of our galaxy or used as target practice by our space vehicles...


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## Max Rigger

snikpoh said:


> Completely off topic but whilst nuclear might be cheap now, the lasting costs of having to dispose of spent fuel rods is enormous - another problem for our children to deal with!!!


Storage of nuclear waste is not cheap but should be safe plus the new generation reactors are extremely safe and reliable. I don't want the need for oil and gas to disappear for around ten to thirteen years mainly because I'm a selfish man who is mortgage and debt free earning a very healthy six figure salary a year working off shore and plan early retirement in ...10-13 years


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## DonMarco

Very interesting topic, especially on-topic posts and posts from members who have solar panels installed and share their experiences.

Thank you.


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## Jamglish

DonMarco said:


> Very interesting topic, especially on-topic posts and posts from members who have solar panels installed and share their experiences.
> 
> Thank you.


An update for the past week of using our new solar panels. It apparently takes some time for the bureaucracy to start crediting us for the power that we return to the grid (2-4 months?). So, for now, we are trying to use up all the power we generate during daylight hours, principally from 12:00 to 16:30. Hopefully in summer we will generate more power and for a longer period from our 2.7 kW peak system. We will probably never achieve the peak because we cannot aim the panels as they are mounted on the roof with whatever orientation and slope they are. Meanwhile, we are running the AC heaters to try and match the power produced, so we are using more power than we would normally. Anyway, from 9-16 Nov we have generated an average of 6.9 kW-hour per day, of which we have managed to use an average of 5.8 kW-hours out of a total consumption of 12 Kw-hours, with the grid supplying 6.2 kW-Hours. The grid supply mostly covers energy used at night/mornings before the panels kick in.


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## DonMarco

Jamglish said:


> An update for the past week of using our new solar panels. It apparently takes some time for the bureaucracy to start crediting us for the power that we return to the grid (2-4 months?). So, for now, we are trying to use up all the power we generate during daylight hours, principally from 12:00 to 16:30. Hopefully in summer we will generate more power and for a longer period from our 2.7 kW peak system. We will probably never achieve the peak because we cannot aim the panels as they are mounted on the roof with whatever orientation and slope they are. Meanwhile, we are running the AC heaters to try and match the power produced, so we are using more power than we would normally. Anyway, from 9-16 Nov we have generated an average of 6.9 kW-hour per day, of which we have managed to use an average of 5.8 kW-hours out of a total consumption of 12 Kw-hours, with the grid supplying 6.2 kW-Hours. The grid supply mostly covers energy used at night/mornings before the panels kick in.


Following this intently........hoping to learn from you.


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## Alcalaina

Well, we’ve hit the first snag. Because we are in a pueblo blanco and the panels will be visible from a footpath on a hill behind our house, the default response is to refuse permission. We are having to appeal to the mayor, who has the ultimate say. Watch this space ...


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## xgarb

You could cover them during the day so they aren't visible and then at night when no one can see them, uncover them.


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## DonMarco

Jamglish said:


> An update for the past week of using our new solar panels. It apparently takes some time for the bureaucracy to start crediting us for the power that we return to the grid (2-4 months?). So, for now, we are trying to use up all the power we generate during daylight hours, principally from 12:00 to 16:30. Hopefully in summer we will generate more power and for a longer period from our 2.7 kW peak system. We will probably never achieve the peak because we cannot aim the panels as they are mounted on the roof with whatever orientation and slope they are. Meanwhile, we are running the AC heaters to try and match the power produced, so we are using more power than we would normally. Anyway, from 9-16 Nov we have generated an average of 6.9 kW-hour per day, of which we have managed to use an average of 5.8 kW-hours out of a total consumption of 12 Kw-hours, with the grid supplying 6.2 kW-Hours. The grid supply mostly covers energy used at night/mornings before the panels kick in.


Jamglish.....What size, i.e.area do your panels cover?


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## Jamglish

DonMarco said:


> Jamglish.....What size, i.e.area do your panels cover?


We have 6 panels, each rated at 450 W peak, for a total of 2.7 kW peak. I think each panel is 2.1m x 1 m. We have 3 of them on a SE facing piece of roof, and 3 on a SW facing piece. They are laid flat on the roof, so not ideal for orientation or tilt, but they seem to do OK. They also share a roof with a solar water heater, so I dont think we have any more roofspace oriented generally to the south. The inverter is mounted vertically on an outside wall, is weatherproof, and feeds into the main electric panel in the house.


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## DonMarco

Jamglish said:


> We have 6 panels, each rated at 450 W peak, for a total of 2.7 kW peak. I think each panel is 2.1m x 1 m. We have 3 of them on a SE facing piece of roof, and 3 on a SW facing piece. They are laid flat on the roof, so not ideal for orientation or tilt, but they seem to do OK. They also share a roof with a solar water heater, so I dont think we have any more roofspace oriented generally to the south. The inverter is mounted vertically on an outside wall, is weatherproof, and feeds into the main electric panel in the house.


Thanks for the info.


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## Jamglish

DonMarco said:


> Thanks for the info.


Here is an update reflecting the past 4 weeks experience (since 8 Nov) with our solar system. The system generated 166 kW-Hr, of which we managed to directly use 136 kW-Hr, and therefore we sent 30 kW-hr back to the grid (currently uncompensated). Our total energy use was 312 kW-Hr, of which the grid supplied 176 kW-Hr (56%). Our energy use was higher than it would be without the solar panels because we tried to use as much of the free energy as we could rather than send it back to the grid (use it or lose it!). So, we turned on heating and ran the washer etc. during the daytime, the opposite of what we did before. The most energy we generated per day was 7.9 kW-Hr (sunny day in early November) while the lowest was 1.2 kW-Hr on a rainy overcast day. As we head towards the end of the month the daily generation will decline a bit along with daylength, but then should start increasing. Hopefully in the middle of summer we will see significantly more daily generation and things like air conditioners will be able to use the free energy, and by then we should be compensated something for what we send back to the grid.


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## Barriej

Jamglish said:


> Here is an update reflecting the past 4 weeks experience (since 8 Nov) with our solar system. The system generated 166 kW-Hr, of which we managed to directly use 136 kW-Hr, and therefore we sent 30 kW-hr back to the grid (currently uncompensated). Our total energy use was 312 kW-Hr, of which the grid supplied 176 kW-Hr (56%). Our energy use was higher than it would be without the solar panels because we tried to use as much of the free energy as we could rather than send it back to the grid (use it or lose it!). So, we turned on heating and ran the washer etc. during the daytime, the opposite of what we did before. The most energy we generated per day was 7.9 kW-Hr (sunny day in early November) while the lowest was 1.2 kW-Hr on a rainy overcast day. As we head towards the end of the month the daily generation will decline a bit along with daylength, but then should start increasing. Hopefully in the middle of summer we will see significantly more daily generation and things like air conditioners will be able to use the free energy, and by then we should be compensated something for what we send back to the grid.


Thanks for this. You make a lot of good points and the main one about zero payback from the grid is probably why solar at home is not as big here as it is in other countries (including the Uk where my father has had a net gain every year for the past 5 or 6).

But this brings up the usual question of battery storage, from my limited experience (I've helped with a couple of installs) the issues going forward will be all about long term (or even mid) storage of the generated power for later use.
After all even with sending back to the grid, at some point if everyone were doing this the grid would become overloaded (so they would need to waste it) until evening when everyone gets home from work, plugs in the electric car, makes tea and watches telly... and up goes the amount of gas etc being burned.

Ive just looked and it appears the costs for batteries are pretty high at the moment.




__





 Solar Batteries


Solar Batteries help you store your excess energy, use it when you need it and save more money with reducing FITs. Learn everything now.




www.dcpowerco.com.au





We can't do solar here in the flat, but at some point when we move it is something i will be looking at (even just for the water along saves money in the long run).

Please keep us updated and thanks again..


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## Alcalaina

Still waiting for permission from the Mayor ...  but the installation company are hopeful because last year Andalucia passed a law (BOJA 2/2020 9.1.20) stripping ayuntamientos of the power to restrict all sorts of things, including this.


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## Alcalaina

Finally got the permiso from the Ayuntamiento this morning, after their initial refusal. It took six visits and a dozen phone calls in all, but persistence paid off. Panels will be installed at the beginning of January.


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## Jamglish

It has been 8 weeks since installing our panels. In the first 4 weeks we used a total of 312 kW-Hr, of which the panels generated 166 kW-Hr, and from which we managed to directly use 136 kW-Hr and ending up sending 30 kW-Hr back to the grid. In the 2nd 4 weeks we used 315 kW-Hr but only generated 104 kW-Hr, out of which we directly used 81 kW-Hr. There was a fair number of cloudy days during the 2nd 4 weeks, which also includes the shortest daylight day of the year. On one rainy day we generated less than 1 kW-Hr, whereas on sunny days we now get a maximum of 5 to 6 kW-Hrs. Early in November we were getting more than 8 kW-Hrs on sunny days. As daylight length is now growing, we should start seeing more. As well as low power generation on cloudy winter days, we use more energy because the solar water heater doesnt do much and we have to use backup electrical water heating. On sunny days we can run the split ac units as heaters around midday while on cloudy days we use the pellet stove. Still waiting for compensation to kick in for energy we send back to the grid, but anyway it wont be much compared to the cost of buying the same energy back. It is interesting (maybe addictive!) to be able to monitor energy generation and use throughout the day on the app, and to see what can be turned on to try and directly use what we generate while not using more from the grid.


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## Alcalaina

Jamglish said:


> It has been 8 weeks since installing our panels. In the first 4 weeks we used a total of 312 kW-Hr, of which the panels generated 166 kW-Hr, and from which we managed to directly use 136 kW-Hr and ending up sending 30 kW-Hr back to the grid. In the 2nd 4 weeks we used 315 kW-Hr but only generated 104 kW-Hr, out of which we directly used 81 kW-Hr. There was a fair number of cloudy days during the 2nd 4 weeks, which also includes the shortest daylight day of the year. On one rainy day we generated less than 1 kW-Hr, whereas on sunny days we now get a maximum of 5 to 6 kW-Hrs. Early in November we were getting more than 8 kW-Hrs on sunny days. As daylight length is now growing, we should start seeing more. As well as low power generation on cloudy winter days, we use more energy because the solar water heater doesnt do much and we have to use backup electrical water heating. On sunny days we can run the split ac units as heaters around midday while on cloudy days we use the pellet stove. Still waiting for compensation to kick in for energy we send back to the grid, but anyway it wont be much compared to the cost of buying the same energy back. It is interesting (maybe addictive!) to be able to monitor energy generation and use throughout the day on the app, and to see what can be turned on to try and directly use what we generate while not using more from the grid.


Your updates are really useful, thank you. Can´t wait to get ours installed - not long to wait now!


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## Alcalaina

Our panels have been in place for ten days now and have been generating an average of 5 kWh a day (though we haven't yet had any really overcast days). At this moment they are generating 1700W and powering two electric radiators. The app is totally addictive....


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## Jamglish

Alcalaina said:


> Our panels have been in place for ten days now and have been generating an average of 5 kWh a day (though we haven't yet had any really overcast days). At this moment they are generating 1700W and powering two electric radiators. The app is totally addictive....


Yes, the app is addictive, and also educational as it lets you see how much energy you are actually using each time you turn something on. For example, backup electrical heating for the rooftop solar hot water tank on a very cloudy day recently required 10kW-Hr, almost all of which had to be bought as the panels generated very little. Then, the decision is whether to turn on the backup water heating during the day when electricity prices are highest but you may get a little help from the panels, or at nightime during a cheaper period, but no solar power help. Its a game trying to work out what can be turned on to use as much as possible of the free energy while not overshooting too much and paying for it.


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## Alcalaina

Jamglish said:


> Yes, the app is addictive, and also educational as it lets you see how much energy you are actually using each time you turn something on. For example, backup electrical heating for the rooftop solar hot water tank on a very cloudy day recently required 10kW-Hr, almost all of which had to be bought as the panels generated very little. Then, the decision is whether to turn on the backup water heating during the day when electricity prices are highest but you may get a little help from the panels, or at nightime during a cheaper period, but no solar power help. Its a game trying to work out what can be turned on to use as much as possible of the free energy while not overshooting too much and paying for it.


Yes, that's a very useful facility. Having seen how high the spike is while the radiators are warming up, I now turn them on at 9.30 am while the price is still lower, and by 10 am when peak hours kick in my office is nice and warm and the panels can cope comfortably with the load.

Have you managed to get your 50% discount on your IBI? Our installer said this was available everywhere but we haven't been to the ayuntamiento yet.


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## jakethepeg

Very interesting thread. I have solar panels on my motorhome, of course on a much smaller scale. With the current cost of electricity, how long before you recoup the cost of the installation?


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## Alcalaina

jakethepeg said:


> Very interesting thread. I have solar panels on my motorhome, of course on a much smaller scale. With the current cost of electricity, how long before you recoup the cost of the installation?


We have eight 2 x 1 metre panels and although it's still early days we estimate it will take about 8 years, or less if the price of electricity continues to rise. The total cost of the installation was just over €4,000. We've applied to the Junta de Andalucia for a grant but don´t hold out much hope as the funds are limited.


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## Jamglish

Alcalaina said:


> Yes, that's a very useful facility. Having seen how high the spike is while the radiators are warming up, I now turn them on at 9.30 am while the price is still lower, and by 10 am when peak hours kick in my office is nice and warm and the panels can cope comfortably with the load.
> 
> Have you managed to get your 50% discount on your IBI? Our installer said this was available everywhere but we haven't been to the ayuntamiento yet.


I didnt know there was an IBI discount. Thanks, I will look into that.


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## Jamglish

Alcalaina said:


> We have eight 2 x 1 metre panels and although it's still early days we estimate it will take about 8 years, or less if the price of electricity continues to rise. The total cost of the installation was just over €4,000. We've applied to the Junta de Andalucia for a grant but don´t hold out much hope as the funds are limited.


How long it takes to start paying for itself depends on various factors, some in our control and some not. It will depend on the price you would have paid if you had to buy the same energy instead of generating your own energy, and that will also depend on the day/time of day that you buy power. Also, the price that you receive from the energy company for whatever you send back to the grid. Actively managing the system will minimize how much and when you need to buy energy, and how much you put back into the grid. Its probably also a safe bet that energy prices will rise, and maybe interest rates also. I am guessing the payback would be about 6-8 years. If you plan on staying put, it will definitely save money in the long run. If not, you would probably recoup at least some of the cost of the solar system when you sell.


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## Jamglish

Jamglish said:


> How long it takes to start paying for itself depends on various factors, some in our control and some not. It will depend on the price you would have paid if you had to buy the same energy instead of generating your own energy, and that will also depend on the day/time of day that you buy power. Also, the price that you receive from the energy company for whatever you send back to the grid. Actively managing the system will minimize how much and when you need to buy energy, and how much you put back into the grid. Its probably also a safe bet that energy prices will rise, and maybe interest rates also. I am guessing the payback would be about 6-8 years. If you plan on staying put, it will definitely save money in the long run. If not, you would probably recoup at least some of the cost of the solar system when you sell.


Another update to mark the 12 weeks since our panels were installed back in November. This covers the depths of an Andalusian winter, which is the most challenging time because of the shorter daylight lengths, the midday sun being lower in the sky, and cloudy/rainy days. The panels are rated at 2.7 kW peak, and are mounted on our best pieces of roof, but their resulting direction and angle are maybe not ideal. So far the best we have done is 1.7 kW on sunny winter days, with about 6-8 kW-Hr generated on such days. On some rainy days we have harvested less than 1 Kw-Hr. I am still waiting to get some compensation for the power that we return to the grid, and am actively managing it to try to minimize the donated energy. During the past 12 weeks we generated a total of 395 kW-Hr, of which we managed to directly use 325 kW-Hr (82%). Our total energy consumption has been 965 kW-Hr, so we had to buy 640 kW-Hr from the grid (about 53 kW-Hr/week), and meanwhile returned a total of 70 kW-Hr back to the grid. On cloudy days there is not much one can do as not much energy is generated. On such days a big user of electricity is backup electrical heating for the solar water heater. Electric heaters stay off and the pellet stove stays on. On sunny days we get free hot water and turning on the right combination of electric heaters and appliances can use most of the energy generated but without using much more than that. If we didn’t have solar panels we would use less total energy but would have to pay for all of it. Using up free energy when it is available means, for example, we can keep the house warmer than we otherwise would. I hope we can reach the rated value of 2.7 kW as day length increases and days are more sunny. After a full year it will be interesting to see how much energy was generated, how much of it was used, how much was returned to the grid, how much the total energy consumption was, and how much our solar energy was worth. This should provide good information to help figure out the payback period for our investment in solar energy in Andalucia (which should be amongst the top places to take advantage of solar energy, both for electricity and water heating).


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## Alcalaina

One thing I’m finding really frustrating is that if there is any hiccup in the mains supply, even for a microsecond, the control unit shuts itself down and we have to reboot it by turning the mains supply off and on again. It’s happened a couple of times while we were out, meaning that we ”lost” all the energy generated on sunny afternoons. Might have to consider some sort of UPS set-up.


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## Jamglish

Alcalaina said:


> One thing I’m finding really frustrating is that if there is any hiccup in the mains supply, even for a microsecond, the control unit shuts itself down and we have to reboot it by turning the mains supply off and on again. It’s happened a couple of times while we were out, meaning that we ”lost” all the energy generated on sunny afternoons. Might have to consider some sort of UPS set-up.


Hmmm. I dont know if ours shuts off after a power cut. So far it has not done so, but I also dont know if there have been any interruptions in the mains power supply since we have installed it. I suppose it depends on whether the inverter can handle interruptions . I will check with the supplier.


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## xgarb

This is probably to protect electricity company workers. They don't want your panels to be feeding into the network if they've cut the power (or even if there's a glitch somewhere) and are fixing cables. If there's no power on their side then your system shouldn't be feeding back. Maybe this is why you have to switch the supply off and on again.


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## Alcalaina

xgarb said:


> This is probably to protect electricity company workers. They don't want your panels to be feeding into the network if they've cut the power (or even if there's a glitch somewhere) and are fixing cables. If there's no power on their side then your system shouldn't be feeding back. Maybe this is why you have to switch the supply off and on again.


It hasn't started feeding into the grid yet, still waiting for the paperwork. It's because the inverter is hypersensitive to fluctuations, according to the installer. Also, it automatically stops feeding into the grid if the mains power is cut off (so we don't get anything during power cuts).


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## olivefarmer

Alcalaina said:


> It hasn't started feeding into the grid yet, still waiting for the paperwork. It's because the inverter is hypersensitive to fluctuations, according to the installer. Also, it automatically stops feeding into the grid if the mains power is cut off (so we don't get anything during power cuts).


very interesting thread. Prices have certainly come down.
Where does the inverter sit in the scheme? Is it at your providers ( eg Endesa) smart meter? How do Endesa know how much electric you have put into their network?


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## Alcalaina

olivefarmer said:


> very interesting thread. Prices have certainly come down.
> Where does the inverter sit in the scheme? Is it at your providers ( eg Endesa) smart meter? How do Endesa know how much electric you have put into their network?


The inverter is a box on a wall inside the house and connected directly into the mains meter with a big green cable, don't ask me the technical details but it's all part of the installation service.. 

The installers are in contact with our supplier (Electrica Cadiz) and once all the paperwork is sorted, the surplus power from the panels will be fed back into the grid and we will be paid something like 6 cents per kWh (or rather, they will deduct it from our bill). Until then, the panels stop generating excess power once supply exceeds usage, as it has nowhere to go

There's an app that tells you how much power you are using in total, how much of that is coming from the panels and how much from the grid. We are currently getting about a third of our power from the panels over a 24 hour period, and we are still using electric radiators.


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## olivefarmer

Alcalaina said:


> The inverter is a box on a wall inside the house and connected directly into the mains meter with a big green cable, don't ask me the technical details but it's all part of the installation service..
> 
> The installers are in contact with our supplier (Electrica Cadiz) and once all the paperwork is sorted, the surplus power from the panels will be fed back into the grid and we will be paid something like 6 cents per kWh (or rather, they will deduct it from our bill). Until then, the panels stop generating excess power once supply exceeds usage, as it has nowhere to go
> 
> There's an app that tells you how much power you are using in total, how much of that is coming from the panels and how much from the grid. We are currently getting about a third of our power from the panels over a 24 hour period, and we are still using electric radiators.


Thanks. We are going to get some quotes.


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## Jamglish

olivefarmer said:


> Thanks. We are going to get some quotes.


Our inverter is mounted on an outside wall with wiring in a conduit connecting it to the breaker box inside. It has been 3 months since the installation and we are still waiting for the bureaucracy to start crediting us for the energy returned to the grid. We were warned at installation that it could take 2-4 months, and until it gets sorted we are essentially "donating" the energy.


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## Jamglish

Another 4 weekly update. Now that we are getting longer daylight lengths my panels have perked up. Recent sunny days and higher sun angles have seen the daily energy generated creep above 10kW-Hr per day, with the peak power getting up to 2kW. The panels have a peak rating of 2.7kW, so hopefully they will hit that in the summer. However on sunny days in the depths of winter we didnt get much more than 5 kW-Hr per day. The eventual performance throughout the year depends on the particular circumstances of orientation etc. If every day in the past 16 weeks were full sun, I would have generated almost 800 kW-Hr. As it is, cloudy days reduced actual energy generation to 600 kW-Hr (75%), of which we managed to directly use 450 kW-Hr (also 75%). Meanwhile, total energy consumption during this 16 weeks was 1300 kW-Hr. We ended up buying 840 kW-Hr while sending 150 kW-Hr back to the grid (still uncompensated!). Looking forward to seeing what we get next month, with longer days and probably fewer cloudy ones.


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## Jamglish

Jamglish said:


> Another 4 weekly update. Now that we are getting longer daylight lengths my panels have perked up. Recent sunny days and higher sun angles have seen the daily energy generated creep above 10kW-Hr per day, with the peak power getting up to 2kW. The panels have a peak rating of 2.7kW, so hopefully they will hit that in the summer. However on sunny days in the depths of winter we didnt get much more than 5 kW-Hr per day. The eventual performance throughout the year depends on the particular circumstances of orientation etc. If every day in the past 16 weeks were full sun, I would have generated almost 800 kW-Hr. As it is, cloudy days reduced actual energy generation to 600 kW-Hr (75%), of which we managed to directly use 450 kW-Hr (also 75%). Meanwhile, total energy consumption during this 16 weeks was 1300 kW-Hr. We ended up buying 840 kW-Hr while sending 150 kW-Hr back to the grid (still uncompensated!). Looking forward to seeing what we get next month, with longer days and probably fewer cloudy ones.


Another 4 week update. We are now into spring and longer days, but this past month has not been particularly good for solar power here in Andalucia because of all the cloudy days. We actually generated a bit less the past 4 weeks than we did during the 4 weeks before that. Under ideal conditions of cloudless days, we could have generated a maximum of 340 kW-Hrs during the past 4 weeks, but only actually reached about half of that. The previous 4 weeks, the maximum possible would have been 250 kW-Hrs but we actually got almost 75% of that. However, it is good that the recent calima dust storms did not appear to coat the panels, with the later mud free rain apparently washing them off. 
Since we installed the panels 20 weeks ago, we have consumed a total of 1600 kW-Hr, out of which the panels generated 780 kW-Hr and of which we managed to directly consume 560 kW-hr while donating 220 Kw-Hrs back to the grid, still without any compensation.


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## olivefarmer

Jamglish said:


> Another 4 week update. We are now into spring and longer days, but this past month has not been particularly good for solar power here in Andalucia because of all the cloudy days. We actually generated a bit less the past 4 weeks than we did during the 4 weeks before that. Under ideal conditions of cloudless days, we could have generated a maximum of 340 kW-Hrs during the past 4 weeks, but only actually reached about half of that. The previous 4 weeks, the maximum possible would have been 250 kW-Hrs but we actually got almost 75% of that. However, it is good that the recent calima dust storms did not appear to coat the panels, with the later mud free rain apparently washing them off.
> Since we installed the panels 20 weeks ago, we have consumed a total of 1600 kW-Hr, out of which the panels generated 780 kW-Hr and of which we managed to directly consume 560 kW-hr while donating 220 Kw-Hrs back to the grid, still without any compensation.


Rightly or wrongly we have just committed to a 16 panel , 7.5 kw array and batteries circa 10k. Three phase invertor. Payback 1000 years or maybe as little as ten.


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## snikpoh

olivefarmer said:


> Rightly or wrongly we have just committed to a 16 panel , 7.5 kw array and batteries circa 10k. Three phase invertor. Payback 1000 years or maybe as little as ten.


What size panels? I guess they are the older ones of 450W?

Why did you choose to use batteries rather than autoconsumo?

Thanks


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## tardigrade

olivefarmer said:


> Rightly or wrongly we have just committed to a 16 panel , 7.5 kw array and batteries circa 10k. Three phase invertor. Payback 1000 years or maybe as little as ten.


1000 sounds more like it if we have the month of March again and again... Hardly saw the sun here in Valencia.


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## Jamglish

olivefarmer said:


> Rightly or wrongly we have just committed to a 16 panel , 7.5 kw array and batteries circa 10k. Three phase invertor. Payback 1000 years or maybe as little as ten.


The way energy prices are going, and may continue to go, I think investing in solar and storage is good. The actual payback period can only be known in hindsight. Having storage eliminates/reduces what you have to send back to the grid for a pittance. Keeping up with the data from the app, keeping the batteries topped up whenever possible and using up any excess somehow seems to be the right strategy, even if you have to turn on heating/cooling etc. that you otherwise might not. During multi day cloudy spells the energy you generate may not be enough. For me, heating water when the solar water heater is insufficient is the biggest consumer of grid energy. I wish I had some battery storage. That is the next phase once I have finished paying for the panels in about 3 years, and hopefully the cost per kW-Hr stored will have come down a bit by then. Good luck with the new system!


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## snikpoh

Jamglish said:


> The way energy prices are going, and may continue to go, I think investing in solar and storage is good. The actual payback period can only be known in hindsight. Having storage eliminates/reduces what you have to send back to the grid for a pittance. Keeping up with the data from the app, keeping the batteries topped up whenever possible and using up any excess somehow seems to be the right strategy, even if you have to turn on heating/cooling etc. that you otherwise might not. During multi day cloudy spells the energy you generate may not be enough. For me, heating water when the solar water heater is insufficient is the biggest consumer of grid energy. I wish I had some battery storage. That is the next phase once I have finished paying for the panels in about 3 years, and hopefully the cost per kW-Hr stored will have come down a bit by then. Good luck with the new system!


My plans are to go "autoconsumo" (no batteries). On that way I don't need to keep topping them up not replace them every few years.

My quotes are for 8.6KW (16 panels at 540W) which (for me) has a payback period of around 4-5 years.

Remember, even when it's cloudy, the panels will produce some power.


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## Jamglish

snikpoh said:


> My plans are to go "autoconsumo" (no batteries). On that way I don't need to keep topping them up not replace them every few years.
> 
> My quotes are for 8.6KW (16 panels at 540W) which (for me) has a payback period of around 4-5 years.
> 
> Remember, even when it's cloudy, the panels will produce some power.


Yes, even on cloudy days there is some energy produced. However, on rainy/drizzly days it is not much. On such days in my case I generated only about 10% - 15% of what would be generated on a sunny day. In the worst week (which was recently) I got 33% of the maximum for the entire 7 days. Hope sunny days return to Andalusia!


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## Turtles

snikpoh said:


> My plans are to go "autoconsumo" (no batteries). On that way I don't need to keep topping them up not replace them every few years.
> 
> My quotes are for 8.6KW (16 panels at 540W) which (for me) has a payback period of around 4-5 years.
> 
> Remember, even when it's cloudy, the panels will produce some power.


Please could you say how much you were quoted for this? I've heard it said that you are doing well if you can pay one euro per watt.


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## Max Rigger

Turtles said:


> Please could you say how much you were quoted for this? I've heard it said that you are doing well if you can pay one euro per watt.


Much less than €1 a watt these days, from a couple of hundred for a 500w panel depending on your budget and needs. Still working on the house (and back to work in a couple of days) so if I'm lucky I'll put together a solar system to power my radio shack by October, 4Kw using AGM batteries and its the batteries that wack the price up.


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## Turtles

Max Rigger said:


> Much less than €1 a watt these days, from a couple of hundred for a 500w panel depending on your budget and needs. Still working on the house (and back to work in a couple of days) so if I'm lucky I'll put together a solar system to power my radio shack by October, 4Kw using AGM batteries and its the batteries that wack the price up.


I actually meant for the whole system, not just the panels - so if you could get 4kw installed for 4,000 euros you'd be doing pretty well. I know that inverters, and of course manpower have not got cheaper at the same rate as the panels.


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## anh12

Turtles said:


> I actually meant for the whole system, not just the panels - so if you could get 4kw installed for 4,000 euros you'd be doing pretty well. I know that inverters, and of course manpower have not got cheaper at the same rate as the panels.


I recently got a quote for a 3.6kW peak system, grid connected, as follows:
8 panels, hybrid inverter, meter, controller, framework, full installation, including 21% IVA: 6450 euros (1.79/W)
4.5KW peak system with 10 panels: as above with IVA: 7450 (1.66/W)
Options:
Battery storage: 5kW, inc. IVA and installation: 4350 euros
Battery storage 10kW, inc IVA and installation: 7738 euros

I imagine it's possible to do it for less, especially if you can do it yourself. This quote was from a very reputable company. I have neighbors who have had major headaches with their installations done by a company without the same reputation, and I'd like to avoid that. I'm not ready to leap yet, but hope to within the next year.


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## Turtles

anh12 said:


> I recently got a quote for a 3.6kW peak system, grid connected, as follows:
> 8 panels, hybrid inverter, meter, controller, framework, full installation, including 21% IVA: 6450 euros (1.79/W)
> 4.5KW peak system with 10 panels: as above with IVA: 7450 (1.66/W)
> Options:
> Battery storage: 5kW, inc. IVA and installation: 4350 euros
> Battery storage 10kW, inc IVA and installation: 7738 euros
> 
> I imagine it's possible to do it for less, especially if you can do it yourself. This quote was from a very reputable company. I have neighbors who have had major headaches with their installations done by a company without the same reputation, and I'd like to avoid that. I'm not ready to leap yet, but hope to within the next year.


Thanks for that. Last week I got a quote from a company that will sell me a 10 panel 4.5kw system for 4500 euros. The trick? The panels do not go on my house, but are installed on a solar farm in Extremadura. They function exactly as if they were on my roof. There is an app to show how much they are producing, and excess production that goes back to the grid is compensated. Excess consumption is charged at PVPC rates. I haven't read all the small print, so I won't make any recommendation. I just thought it made a lot of sense to do it this way. My own roof is an odd shape and there are some nearby fast-growing trees that will put the house in shade in years to come. The economies of scale of buying a tiny portion of someone's massive farm rather than getting your own set up have got to be considerable. There also wouldn't be any delay or ayuntamiento paperwork to deal with. I'd expect this to be the norm in the future. I'll be keeping an eye on this for when my fixed tariff with Endesa Unica comes to an end.


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## kalohi

anh12 said:


> I recently got a quote for a 3.6kW peak system, grid connected, as follows:
> 8 panels, hybrid inverter, meter, controller, framework, full installation, including 21% IVA: 6450 euros (1.79/W)
> 4.5KW peak system with 10 panels: as above with IVA: 7450 (1.66/W)
> Options:
> Battery storage: 5kW, inc. IVA and installation: 4350 euros
> Battery storage 10kW, inc IVA and installation: 7738 euros
> 
> I imagine it's possible to do it for less, especially if you can do it yourself. This quote was from a very reputable company. I have neighbors who have had major headaches with their installations done by a company without the same reputation, and I'd like to avoid that. I'm not ready to leap yet, but hope to within the next year.


We've recently been getting quotes and what you've written here coincides with the quotes we've been getting. So far we have 3 different quotes and they're all pretty much the same. It's hard to know which one is the best one to go with.


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## tardigrade

kalohi said:


> We've recently been getting quotes and what you've written here coincides with the quotes we've been getting. So far we have 3 different quotes and they're all pretty much the same. *It's hard to know which one is the best one to go with*.


Are there places on the intranet to look for customer feedback?

Is there a location like Companies House in the UK or URSSAF in France where you can check out a business - time open, capital, etc.. in Spain?

Have never had to check out a company here in Spain for a major purchase but if I did I would follow the ways I would have done in the country I last did it in. It would probably be the same steps.


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## Jamglish

Our system, 2.7 kWatt peak, worked out at a bit over 2 euro/Watt for a complete system (panels, inverter, installation on the roof and whatever paperwork is needed to get credit for what we supply back to the grid. Still waiting for the latter after 20 weeks, but it probably wont amount to much (I was told about 0.06 euro/kW-Hr). Once I actually start getting some credit I will let you know. I dont know if our cost is about average or whether we overpaid a bit. For any particular system and on any particular day of the year, there will be a maximum amount it can produce if that day is clear. For my system, the daily energy production on a clear day was only about 5 kW-Hr in the dead of winter. Now, it should be about 14 kW-Hr/day, although clear days to check this have been in short supply. Maybe by mid-summers day in June I will get about 20 kW-Hr.


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## ariescat

Not very computer savvy so hope this gets posted. I had 2 batteries and 10 panels installed beginning of Sept 2021. The best decision I ever made. But anyone who thinks they will make anything worthwhile from unused capacity returned to the grid is in cloud cuckoo land. Iberdrola took 7 months to agree to pay the 0.05 for power i send back to the grid. So the April bill just received is the first to show the pay back, called 'excedentes' (autoconsumo). They credited €18,33 (gosh, I got so excited!) but in the next column, took back €14,11 under a second heading which reads Autoconsumo No Compensable. The balance of credit is therefore only €4,22. If this happens every month of sunny weather, I'm all set to make less than €50 by the end of the year. And it means that the real credited payment works out at less than 2 cents, not the promised 5 cents. I have no clue why more than 75% of the promised payment for unused capacity is clawed back by them. The Solar supplier doesn't understand it either. I'm waiting for a reply from the electricity company but not holding my breath. Does anyone on this forum have any idea what this means?


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## Max Rigger

Panels are cheap enough, its the batteries that cost the big bucks


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## tardigrade

I have been in this business for 15+ years... Please do not expect any positive gain(€) from the energy companies if you put your unused watts into the grid. Will not happen on a house. Yes, as stated, 4 or even 10 euros a month.. They will find ways to negate your input... 
There are other ways ( a little investment up front) to charge the batteries - flush the toilet, use the sink(s) using a turbine, a combo system with a small wind turbine... You can even make your own battery








Making Your Own Lithium-ion Batteries


You can make your own lithium-ion batteries if you have a source for individual cells and a control board to match your desired voltage levels. [Bill Porter] put together a quick tutorial where he …




hackaday.com





or your own "gaz" plant...





Make a Biogas Generator to Produce Your Own Natural Gas – Mother Earth News


Transform grass clippings, food waste and livestock manure into renewable energy via a homemade biogas generator.



www.motherearthnews.com





which could charge your batteries...

It is nice to think that you are doing good but that solar panel takes so much energy to make that it will never produce enough to offset that.

Think "out of the box" and not what they tell you... That will always be true until the petrol runs out...


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## Max Rigger

I love thinking out of the box and DIY (its the engineer/radio ham in me), but for most people DIY energy projects won't happen due to lack of skills, lack of space, lack of money, location (wind power or hydro projects) et al plus with off the shelf products you get the finished product ready to rock and roll.


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## dancingspider

Max Rigger said:


> its the engineer/radio ham in me)


Can you just transmit here on 27Mhz or AM/FM here in Spain or do you need a licence or do exams or something?

I brought a few AM/FM/SSB rigs with me from the UK. Living in a bit of a dip here in the landscape at the moment so location isn't ideal. Hooked up to a mag antenna but could hear anyone.


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## Jamglish

A quick update on my experience with the panels installed last November, so far covering a winter, spring and most of a summer. The system is rated at 2.7 KW peak, and occupies two sections of roof at whatever angle the roof is. The ideal orientation is south facing at the optimum angle, but our two sections of roof face approximately SE and SW. The system is therefore not ideal. In December, we only generated a total of 126 KW-hr, of which we managed to directly use 101 kW-hr. Total use that month was 350 KW-hr. In May, we generated a lot more, 414 KW-hr, but only directly used 150 KW-hr because heating, air conditioning, and water heating, the major energy consumers, were not needed. Hot water comes from a solar water heater, and in May the sun is enough to supply all the hot water used and the weather is excellent. The total consumption was only 245 KW-hr, so a lot of the energy ended up going back to the grid for free. There is just not much need for energy then, unless you want to run electric kettles, ovens or toasters all day all day!. In contrast, in July we generated 387 KW-hr and managed to directly use 318 KW-hrs through running air conditioning. The total consumption was 526 KW-hr because we ran air conditioning that we wouldnt have if we didnt have solar panels. So, it was nice to be cool during the day without having to pay the price. We ended up only buying 208 KW-hr, and only sent 70 KW-hr back to the grid. The system so far has never achieved its 2.7 KW peak. Hosing off the panels recently to reduce dust/ash etc gained about one extra KW-hr per day. So far, we are happy with the investment because of having to buy less energy and to be able to use more energy in summer for cooling. But still no compensation for the almost 900 KW-hr we have sent back to the grid from December to July!.


----------



## kaipa

Jamglish said:


> A quick update on my experience with the panels installed last November, so far covering a winter, spring and most of a summer. The system is rated at 2.7 KW peak, and occupies two sections of roof at whatever angle the roof is. The ideal orientation is south facing at the optimum angle, but our two sections of roof face approximately SE and SW. The system is therefore not ideal. In December, we only generated a total of 126 KW-hr, of which we managed to directly use 101 kW-hr. Total use that month was 350 KW-hr. In May, we generated a lot more, 414 KW-hr, but only directly used 150 KW-hr because heating, air conditioning, and water heating, the major energy consumers, were not needed. Hot water comes from a solar water heater, and in May the sun is enough to supply all the hot water used and the weather is excellent. The total consumption was only 245 KW-hr, so a lot of the energy ended up going back to the grid for free. There is just not much need for energy then, unless you want to run electric kettles, ovens or toasters all day all day!. In contrast, in July we generated 387 KW-hr and managed to directly use 318 KW-hrs through running air conditioning. The total consumption was 526 KW-hr because we ran air conditioning that we wouldnt have if we didnt have solar panels. So, it was nice to be cool during the day without having to pay the price. We ended up only buying 208 KW-hr, and only sent 70 KW-hr back to the grid. The system so far has never achieved its 2.7 KW peak. Hosing off the panels recently to reduce dust/ash etc gained about one extra KW-hr per day. So far, we are happy with the investment because of having to buy less energy and to be able to use more energy in summer for cooling. But still no compensation for the almost 900 KW-hr we have sent back to the grid from December to July!.


Good post. First time I seen actual details of what solar panels here in spain actually will do and it provides an honest balance of things. You also seem to provide an honest account of your consumption levels. Question is: how much was the total installation cost? We had a reunion in the building last month and decided that installing solar panels was still way too expensive.


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## dancingspider

Jamglish said:


> A quick update on my experience with the panels installed last November, so far covering a winter, spring and most of a summer. The system is rated at 2.7 KW peak, and occupies two sections of roof at whatever angle the roof is. The ideal orientation is south facing at the optimum angle, but our two sections of roof face approximately SE and SW. The system is therefore not ideal. In December, we only generated a total of 126 KW-hr, of which we managed to directly use 101 kW-hr. Total use that month was 350 KW-hr. In May, we generated a lot more, 414 KW-hr, but only directly used 150 KW-hr because heating, air conditioning, and water heating, the major energy consumers, were not needed. Hot water comes from a solar water heater, and in May the sun is enough to supply all the hot water used and the weather is excellent. The total consumption was only 245 KW-hr, so a lot of the energy ended up going back to the grid for free. There is just not much need for energy then, unless you want to run electric kettles, ovens or toasters all day all day!. In contrast, in July we generated 387 KW-hr and managed to directly use 318 KW-hrs through running air conditioning. The total consumption was 526 KW-hr because we ran air conditioning that we wouldnt have if we didnt have solar panels. So, it was nice to be cool during the day without having to pay the price. We ended up only buying 208 KW-hr, and only sent 70 KW-hr back to the grid. The system so far has never achieved its 2.7 KW peak. Hosing off the panels recently to reduce dust/ash etc gained about one extra KW-hr per day. So far, we are happy with the investment because of having to buy less energy and to be able to use more energy in summer for cooling. But still no compensation for the almost 900 KW-hr we have sent back to the grid from December to July!.


Very good post and possibly a cautionary note to those who want to cover every available inch of roof with panels....

My understanding is that sometimes if you inject energy into the grid you are compensated for it. Perhaps that is in the UK or elsewhere. Can you clarify?


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## Alcalaina

We had eight panels installed with a total capacity of 5 kW in January. To date they have generated 1,445 kWh, just under half the total used. This obviously varies by month, in June it was 70%. We still aren't sending the surplus into the grid - the inverter only generates what we are using. The installation cost €4,000 but I've no idea how much we've saved. Our last bill (June) was €41.

It's great to be able to leave all four air-con units running all day, and not worry about using the oven etc in peak hours.


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## Alcalaina

dancingspider said:


> My understanding is that sometimes if you inject energy into the grid you are compensated for it. Perhaps that is in the UK or elsewhere. Can you clarify?


In theory yes, but in practice ... and when they do get round to paying it's only a few cents per kWh.


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## dancingspider

So they charge more per kWh for consumption versus injected energy?

What are the exact numbers please?


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## Jamglish

Yes, they give you much less than they charge for the same amount of energy. And it takes a long time to even get anything back. It is better to use the energy directly if you can rather than send it back to the grid. Storing the excess energy for later use would be better than getting a pittance for it from the grid (5-6 c/KW-hr I believe), but until battery storage gets cheaper (or when electric cars can be used to store and supply domestic energy), storage is not economically viable. Using excess to heat water for domestic use could be an option under the right circumstances. Anyway, for now I try and directly use as much of the energy as I can by keeping an eye on the app that tells me how much I am generating and consuming at any time, as it is essentially a "use it or lose it" situation. The inverter can be set up to prevent power going back to the grid, but as I understand it, the system will then reduce the power being supplied if it is not going to be either used or sent back. As soon as I eventually get compensated for what goes to the grid I will let you know the exact numbers.


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## Jamglish

Alcalaina said:


> We had eight panels installed with a total capacity of 5 kW in January. To date they have generated 1,445 kWh, just under half the total used. This obviously varies by month, in June it was 70%. We still aren't sending the surplus into the grid - the inverter only generates what we are using. The installation cost €4,000 but I've no idea how much we've saved. Our last bill (June) was €41.
> 
> It's great to be able to leave all four air-con units running all day, and not worry about using the oven etc in peak hours.


Yes, the comfort of running air conditioning in summer (and maybe some heating in winter) at little or no cost is worth a lot to the quality of life!. It is hard to know actual money savings because it depends on how much the energy would have cost at different times during the day, and whether one would have used the same energy if it wasnt being supplied free from the solar system.


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## DonMarco

Jamglish said:


> A quick update on my experience with the panels installed last November, so far covering a winter, spring and most of a summer. The system is rated at 2.7 KW peak, and occupies two sections of roof at whatever angle the roof is. The ideal orientation is south facing at the optimum angle, but our two sections of roof face approximately SE and SW. The system is therefore not ideal. In December, we only generated a total of 126 KW-hr, of which we managed to directly use 101 kW-hr. Total use that month was 350 KW-hr. In May, we generated a lot more, 414 KW-hr, but only directly used 150 KW-hr because heating, air conditioning, and water heating, the major energy consumers, were not needed. Hot water comes from a solar water heater, and in May the sun is enough to supply all the hot water used and the weather is excellent. The total consumption was only 245 KW-hr, so a lot of the energy ended up going back to the grid for free. There is just not much need for energy then, unless you want to run electric kettles, ovens or toasters all day all day!. In contrast, in July we generated 387 KW-hr and managed to directly use 318 KW-hrs through running air conditioning. The total consumption was 526 KW-hr because we ran air conditioning that we wouldnt have if we didnt have solar panels. So, it was nice to be cool during the day without having to pay the price. We ended up only buying 208 KW-hr, and only sent 70 KW-hr back to the grid. The system so far has never achieved its 2.7 KW peak. Hosing off the panels recently to reduce dust/ash etc gained about one extra KW-hr per day. So far, we are happy with the investment because of having to buy less energy and to be able to use more energy in summer for cooling. But still no compensation for the almost 900 KW-hr we have sent back to the grid from December to July!.


Excellent report as always. Thank you, from the horses mouth making deciding alot easier.


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## kaipa

Alcalaina said:


> We had eight panels installed with a total capacity of 5 kW in January. To date they have generated 1,445 kWh, just under half the total used. This obviously varies by month, in June it was 70%. We still aren't sending the surplus into the grid - the inverter only generates what we are using. The installation cost €4,000 but I've no idea how much we've saved. Our last bill (June) was €41.
> 
> It's great to be able to leave all four air-con units running all day, and not worry about using the oven etc in peak hours.


The 4 000 € cost is okay but for how long will they effectively operate? We were told in the community that despite installation costs we would need to be prepared to upgrade and pay for potential running costs. Once we crunched the numbers it wasnt cost effective and unfortunately the moral- social responsibility factor doesn't cut the mustard with folk on small pensions or low salaries.


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## Jamglish

kaipa said:


> The 4 000 € cost is okay but for how long will they effectively operate? We were told in the community that despite installation costs we would need to be prepared to upgrade and pay for potential running costs. Once we crunched the numbers it wasnt cost effective and unfortunately the moral- social responsibility factor doesn't cut the mustard with folk on small pensions or low salaries.


My 2 cents worth. I believe the panels themselves should produce a reasonably high percentage of their rated power for 20-25 years, and should come with a guarantee if purchased from a reputable company that is likely to be around during that time. The inverter should be good for 10+ years, and also have an appropriate guarantee. Other than that, maybe a bit of maintenance (cleaning the panels sometimes?). I am no economist, but I dont know what you considered under upgrading and running costs. More panels, larger inverter etc.? There will always be newer and improved technology coming along, like anything else (cars, phones, etc..). But as long as the system works as originally intended, I think the major unknown in a lifetime cost/benefit analysis is the future price of electricity, and maybe the cost of financing the purchase. Regardless, a solar system is definitely a long term investment and is by no means a no-brainer. A solar water heater however, at least in southern Spain, is easy to justify I think.


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## dancingspider

"A degradation rate of 0.5% implies that production from a solar panel will decrease at a rate of 0.5% per year."

STAT FAQs Part 2: Lifetime of PV Panels

Power output reduction of panels is very well characterized.

It is a critical parameter when estimating solar farm power yield over the lifetime of the solar farm.

The output power in turn is fed into a financial model of the profit yield from a solar farm. This is a critical part of the tendering process, from commercial solar farms.

Point is that the reduction in output is well understood. Panels do vary in quality and any spec from China isn't worth the paper it is printed on, but regardless the power output should be close to what is specified.


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## olivefarmer

Should I think about installing solar panels?


How many panels would I need? Is it worth having batteries? With the help of experts in the sector, SUR answers some of the most common questions




www.surinenglish.com





Good article of things to consider regarding solar


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## Jamglish

olivefarmer said:


> Should I think about installing solar panels?
> 
> 
> How many panels would I need? Is it worth having batteries? With the help of experts in the sector, SUR answers some of the most common questions
> 
> 
> 
> 
> www.surinenglish.com
> 
> 
> 
> 
> 
> Good article of things to consider regarding solar


Good article. I wonder what the story is on the subsidies mentioned. A subsidy for battery storage could make them economical.


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## dancingspider

The economic drivers for installing panels have changed significantly, due to the recent price hikes for the various types of energy. Russia as a supplier is going to be blacklisted for years.

The payback period on an investment on solar / battery will have shortened. I couldn't quantify that but I am sure it is being documented as we speak as many firms use exactly this info to flow their renewable solutions to customers.


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## Glynb

We had a solar system installed a couple of weeks back, 7 panels plus battery. We are happy with it in general, but something is really puzzling and doesn't make any sense.

On several occasions the system takes from the grid, even though the battery is fully charged and the panels are producing more than enough to match our consumption.

Surely the system should drain the battery as a priority before taking any energy from the grid?

Can anyone explain what's going on? Is this normal? Or is our system not set up correctly? Hopefully I have attached a screenshot from the app demonstrating the issue. Is it to do with wattage or voltage or the "wrong kind of electricity" 😂


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## Barriej

Glynb said:


> We had a solar system installed a couple of weeks back, 7 panels plus battery. We are happy with it in general, but something is really puzzling and doesn't make any sense.
> 
> On several occasions the system takes from the grid, even though the battery is fully charged and the panels are producing more than enough to match our consumption.
> 
> Surely the system should drain the battery as a priority before taking any energy from the grid?
> 
> Can anyone explain what's going on? Is this normal? Or is our system not set up correctly? Hopefully I have attached a screenshot from the app demonstrating the issue. Is it to do with wattage or voltage or the "wrong kind of electricity" 😂


Cant comment on your system, but the screenshot shows the battery at 67%, I'm assuming the setup will pass as much to the battery during generating hours as it can and then to the house and any shortfall (which is shown by adding the amount going to the battery and the house minus the generation) would pull the remaining usage from the grid.
Again assuming that the system is programmed the battery will not supply the house until the solar panels drop below a set amount or at x time when the sun goes down.

OR is the system set that the battery is just a backup in case of grid failure (a friend in the states had this with his Tesla wall as the town he lives in has blackouts). Or only gets used when the supplied grid power is at the highest rate???

I have a solar powered weather station that is also connected to the mains, thats how I have it configured so I get a full battery (as as much as possible) for use at night, the mains runs the station and charges the battery if the solar cell doesn't produce enough.

You need to contact the installer and ask how the system is setup and if you have any control over switching.


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## Glynb

Ok thanks. I guess it must be programmed along lines you describe. I just assumed it would meet demand from battery with the grid as last resort at all times, but seems it charges the battery first even at cost of taking from the grid.

I suppose it makes sense to go into the nightime period with a full battery as priority . I've attached another screenshot with battery at 93% but still taking from the grid even though the pannels could meet household demand.


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## Jamglish

Glynb said:


> Ok thanks. I guess it must be programmed along lines you describe. I just assumed it would meet demand from battery with the grid as last resort at all times, but seems it charges the battery first even at cost of taking from the grid.
> 
> I suppose it makes sense to go into the nightime period with a full battery as priority . I've attached another screenshot with battery at 93% but still taking from the grid even though the pannels could meet household demand.





Glynb said:


> Ok thanks. I guess it must be programmed along lines you describe. I just assumed it would meet demand from battery with the grid as last resort at all times, but seems it charges the battery first even at cost of taking from the grid.
> 
> I suppose it makes sense to go into the nightime period with a full battery as priority . I've attached another screenshot with battery at 93% but still taking from the grid even though the pannels could meet household demand.


Interesting!. I wonder if there is a max and min power required to charge the battery. In both cases it looks like about 0.3 kW is charging the battery. What is the battery capacity (kW-Hr, and what do you get per kW-hr for compensation for the power you put back into the grid?. Is it constant or does it depend on the time of day like the cost of buying power?. I have finally just received notice, 9 months after installation, that I will start getting compensated, but I dont know how much until I see the next bill.


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## Glynb

Jamglish said:


> What is the battery capacity (kW-Hr, and what do you get per kW-hr for compensation for the power you put back into the grid?. Is it constant or does it depend on the time of day like the cost of buying power?.


In our area the main energy company is Iberdrola. Apparently they usually buy for 5 cents a kw. Apparently you can switch to others who offer higher rates, but all in due course.

Nothing happens until we get a certificate from the Ministry and they inform Iberdrola who then start to compensate us. I'm not holding my breath, I suppose it'll happen eventually. A gestor is on the job, it was all part of the deal. Maybe a couple of months?

I fully expect by the time we start to see any income it'll be the winter period low sunshine 😂. Of course we're still saving by using from the panels (day) and battery (night) in the meantime. We've never used the aircon before due to cost - energy waste, now it's on all the time as it's 'free'' !

As to the battery capacity, it's 5 kilowatt.

Does your converter get hot? Ours was so hot the other day I couldn't keep my hand on longer than a second. You'd think they'd fit fans to cool it down, like a computer CPU?


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## olivefarmer

Glynb said:


> In our area the main energy company is Iberdrola. Apparently they usually buy for 5 cents a kw. Apparently you can switch to others who offer higher rates, but all in due course.
> 
> Nothing happens until we get a certificate from the Ministry and they inform Iberdrola who then start to compensate us. I'm not holding my breath, I suppose it'll happen eventually. A gestor is on the job, it was all part of the deal. Maybe a couple of months?
> 
> I fully expect by the time we start to see any income it'll be the winter period low sunshine 😂. Of course we're still saving by using from the panels (day) and battery (night) in the meantime. We've never used the aircon before due to cost - energy waste, now it's on all the time as it's 'free'' !
> 
> As to the battery capacity, it's 5 kilowatt.
> 
> Does your converter get hot? Ours was so hot the other day I couldn't keep my hand on longer than a second. You'd think they'd fit fans to cool it down, like a computer CPU?


my Plus Energy invertor has fans and filters that need cleaning regularly. It is also quite noisy as a result.


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## Glynb

I guess every solution to a problem has some side effects.


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## MataMata

Jamglish said:


> as it is essentially a "use it or lose it" situation.


Not necessarily, there is a balance to be struck between working the batteries (to their possible detriment) and drawing from the grid.


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## Glynb

So are you saying the system balances the take in order to avoid working the batteries to virtually empty every day, which might shorten their life? Drawing from the grid to be reduce battery wear n tear? Or what? Just trying to understand how it works.


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## Glynb

So there are two tariffs available for compensating us for "spare" solar energy supplied back to the grid. The first is a fixed rate at around 5 cents per kwh, the second is variable and higher at 12 cents kwh. Why would anyone choose the fixed rate when the variable is so much higher? Can anyone explain pros and cons?


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## dancingspider

Alcalaina said:


> We had eight panels installed with a total capacity of 5 kW in January. To date they have generated 1,445 kWh, just under half the total used. This obviously varies by month, in June it was 70%. We still aren't sending the surplus into the grid - the inverter only generates what we are using. The installation cost €4,000 but I've no idea how much we've saved. Our last bill (June) was €41.
> 
> It's great to be able to leave all four air-con units running all day, and not worry about using the oven etc in peak hours.


I have an standalone air con unit beside me and it is rated at 2450 watts. I imagine the external ones are also in the range of 2kW+ so I am a bit puzzled by the above statement that you can leave 4 of them running all day with no issue. By my simple arithmetic, 4 aircon units at 2kW is 8kW and you panels have a maximum output at 5kW, so realistically the panel output power is even below 5kW normally. So, what am if failing to understand as the basic maths don't work to have 4 aircon unit running off your panels? Maybe if you have batteries also you can use this reserve to keep the air con units running?


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## kalohi

Air conditioning units with inverter technology (which includes all modern, external units) only run at 100% capacity until the desired temperature is reached in the room. Then to maintain the temperature they draw about 50% less electricity. So they're very economical to run compared to older, non-inverter units. 

We have 9 solar panels installed with a total capacity of about 4000kw, and with the solar power app we can see exactly how much electricity we're using (either from the panels or from the grid) in real time. We can see that all of our A/C units draw about 1000kw when first turned on, and then drop to about 500kw after running for a while. So we can run 4 A/C units at the same time with no problem.


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## olivefarmer

kalohi said:


> Air conditioning units with inverter technology (which includes all modern, external units) only run at 100% capacity until the desired temperature is reached in the room. Then to maintain the temperature they draw about 50% less electricity. So they're very economical to run compared to older, non-inverter units.
> 
> We have 9 solar panels installed with a total capacity of about 4000kw, and with the solar power app we can see exactly how much electricity we're using (either from the panels or from the grid) in real time. We can see that all of our A/C units draw about 1000kw when first turned on, and then drop to about 500kw after running for a while. So we can run 4 A/C units at the same time with no problem.


Do you have batteries? If so,is the system configured to stop using batteries and revert to grid when battery capacity gets to a pre set threshold of say 20% or do the flat each night and then revert to grid? What do other people have theirs set to?


----------



## kalohi

olivefarmer said:


> Do you have batteries? If so,is the system configured to stop using batteries and revert to grid when battery capacity gets to a pre set threshold of say 20% or do the flat each night and then revert to grid? What do other people have theirs set to?


No, no batteries so I can't help you with that.


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## Jamglish

kalohi said:


> Air conditioning units with inverter technology (which includes all modern, external units) only run at 100% capacity until the desired temperature is reached in the room. Then to maintain the temperature they draw about 50% less electricity. So they're very economical to run compared to older, non-inverter units.
> 
> We have 9 solar panels installed with a total capacity of about 4000kw, and with the solar power app we can see exactly how much electricity we're using (either from the panels or from the grid) in real time. We can see that all of our A/C units draw about 1000kw when first turned on, and then drop to about 500kw after running for a while. So we can run 4 A/C units at the same time with no problem.


Yes, you are correct. Without knowing the technology but looking at the app (probably way too much!), our ac units show the same pattern of using briefly close to their rated capacity when turned on, then dropping down a little until the set temperature is reached, after which they apparently cycle between being off and about 50% of rated power. However, my current strategy (rightly or wrongly) is to run the largest ac unit in the living/dining room at full blast as soon as the panels are producing enough power in the morning and keeping it that way by setting the temperature low until later in the afternoon when the solar power drops down again, after which I can raise the temperature setting or turn it off. My thinking is to use as much as I can of the power when it is available rather than giving it free or for a pittance back to the grid. The room then will retain some of this extra cold until later in the day. If I didnt have solar power, or if I had batteries, life would be simpler as I would just set the ac at a reasonable temperature and let it do its efficient thing. Looking forward to getting some battery storage when the price is right, or when an electric car can be the battery.


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## dancingspider

kalohi said:


> _*Air conditioning units with inverter technology (which includes all modern, external units) only run at 100% capacity until the desired temperature is reached in the room. Then to maintain the temperature they draw about 50% less electricity. So they're very economical to run compared to older, non-inverter units.*_
> 
> _*We have 9 solar panels installed with a total capacity of about 4000kw, and with the solar power app we can see exactly how much electricity we're using (either from the panels or from the grid) in real time. We can see that all of our A/C units draw about 1000kw when first turned on, and then drop to about 500kw after running for a while. So we can run 4 A/C units at the same time with no problem.*_


Well then, I guest you must be a hobbit and live in the shire in one of those little houses with round doors!

1kW doesn't get a look in! See link...

A guide to air conditioner sizes | Total Electrics and Air Conditioning


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## Jamglish

dancingspider said:


> Well then, I guest you must be a hobbit and live in the shire in one of those little houses with round doors!
> 
> 1kW doesn't get a look in! See link...
> 
> A guide to air conditioner sizes | Total Electrics and Air Conditioning


No. If you read further, the input electric power is not the same as the cooling power. Air conditioners, refrigerators, and heat pumps do not convert electrical energy, they just move energy. Check out this thread for an explanation on why we are not hobbits.


https://forums.whirlpool.net.au/archive/2330433


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## Barriej

kalohi said:


> Air conditioning units with inverter technology (which includes all modern, external units) only run at 100% capacity until the desired temperature is reached in the room. Then to maintain the temperature they draw about 50% less electricity. So they're very economical to run compared to older, non-inverter units.
> 
> We have 9 solar panels installed with a total capacity of about 4000kw, and with the solar power app we can see exactly how much electricity we're using (either from the panels or from the grid) in real time. We can see that all of our A/C units draw about 1000kw when first turned on, and then drop to about 500kw after running for a while. So we can run 4 A/C units at the same time with no problem.


That is correct, and the smaller the difference between the temperatures the more efficient the A/C units are.
If the outside temp is lets say 30c then the inside temp should not be set lower than around 22c as the unit will run at maximum for longer. 
And to be honest most of them (even new ones) will struggle to drop the temp more than 10 degrees.
We have units with a maximum low setting of 20c for cooling anyway.

Ours are 15 years old and Ive had the operating unit upgraded to give inside and outside temps on the display and we can then set fast chill or slow reduction. 
The slow reduction uses way less power than the fast chill.
And as commented once at temp most units switch to a low use to maintain.
Once ours to the low temp the unit switches to fan only and only starts chilling again after a 2 degree rise.

Although to be honest I don't like cold A/C because, you have a nice cool room and then go outside and it feels like an oven and you never get used to the heat.
Id much rather open all the windows and let what air there is just circulate. We have light weight summer curtains and drawing these gives shade in the room but the air is still free to move around.


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## Alcalaina

dancingspider said:


> I have an standalone air con unit beside me and it is rated at 2450 watts. I imagine the external ones are also in the range of 2kW+ so I am a bit puzzled by the above statement that you can leave 4 of them running all day with no issue. By my simple arithmetic, 4 aircon units at 2kW is 8kW and you panels have a maximum output at 5kW, so realistically the panel output power is even below 5kW normally. So, what am if failing to understand as the basic maths don't work to have 4 aircon unit running off your panels? Maybe if you have batteries also you can use this reserve to keep the air con units running?


We have one large inverter on the roof with four units connected to it, over two floors. Much more energy-efficient than single ones although the initial investment was higher. Even when they are all on, set at 26ºC with the fan on Low, they don't use more than 3kW.


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## sadlybroke

Interesting thread. We are building a villa in Benalmadena, due to be completed in 2-3 months. I want to have the PV panels and batteries installed. I contacted 6 companies several days ago; two of them got back to me, plus I have a quote from our electrician who doesn't specialise in PV installations but has some experience in it (including his own house). It seems that the prices I have been quoted are much higher than what some of you mentioned here. I know our system is quite large but still it seems a bit more expensive than what I expected. 

I told each company about our house and our lifestyle. Based on this, they suggested the size of the system and quoted as follows:

*Local electrician (Spanish):*
14 x 450 WP panels .. €9,100 + VAT
1 x 5 KW accumulation kit ... €5,250 + VAT
2 x 5 KW batteries ... €6,500 + VAT
TOTAL ... €20,850 + VAT

*Local specialised company (option 1):*
16 x 450 panels ... €9,500 + VAT
10 kW batteries ... €6,400 + VAT
TOTAL ... €15,900 + VAT

*Local specialised company (option 2):*
22 x 450 panels ... €12,400 + VAT
15 kW batteries ... €9,200 + VAT
TOTAL ... €21,600 + VAT

*A reputable company from Almeria:*
No quotation yet but an indication that the system will cost over €25,000.

So, the local electrician suggests fewer panels but a bigger battery pack. Also, there is a difference in the suggested size of the system - both panels and the battery pack. 

I know next to nothing about the subject and I also understand that it is difficult to estimate the level of electricity usage without any history (not in this house or country). I think it would be sensible to start small, see how it goes, and extend the system later. However, since we are still building the house, we can benefit from a lower VAT rate (10%) so any investment that we make now would be 11% cheaper just because of that.

I'd be interested in knowing your opinion from the user's point of view. I know you are not experts, I talk to them as well.

Also, if you can recommend a PV installer who covers the Costa del Sol area and who you have genuinely good experience with, please let me know either in the forum (if the rules allow that) or by sending me a PM.

Thank you.


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## kalohi

sadlybroke said:


> Interesting thread. We are building a villa in Benalmadena, due to be completed in 2-3 months. I want to have the PV panels and batteries installed. I contacted 6 companies several days ago; two of them got back to me, plus I have a quote from our electrician who doesn't specialise in PV installations but has some experience in it (including his own house). It seems that the prices I have been quoted are much higher than what some of you mentioned here. I know our system is quite large but still it seems a bit more expensive than what I expected.
> 
> I told each company about our house and our lifestyle. Based on this, they suggested the size of the system and quoted as follows:
> 
> *Local electrician (Spanish):*
> 14 x 450 WP panels .. €9,100 + VAT
> 1 x 5 KW accumulation kit ... €5,250 + VAT
> 2 x 5 KW batteries ... €6,500 + VAT
> TOTAL ... €20,850 + VAT
> 
> *Local specialised company (option 1):*
> 16 x 450 panels ... €9,500 + VAT
> 10 kW batteries ... €6,400 + VAT
> TOTAL ... €15,900 + VAT
> 
> *Local specialised company (option 2):*
> 22 x 450 panels ... €12,400 + VAT
> 15 kW batteries ... €9,200 + VAT
> TOTAL ... €21,600 + VAT
> 
> *A reputable company from Almeria:*
> No quotation yet but an indication that the system will cost over €25,000.
> 
> So, the local electrician suggests fewer panels but a bigger battery pack. Also, there is a difference in the suggested size of the system - both panels and the battery pack.
> 
> I know next to nothing about the subject and I also understand that it is difficult to estimate the level of electricity usage without any history (not in this house or country). I think it would be sensible to start small, see how it goes, and extend the system later. However, since we are still building the house, we can benefit from a lower VAT rate (10%) so any investment that we make now would be 11% cheaper just because of that.
> 
> I'd be interested in knowing your opinion from the user's point of view. I know you are not experts, I talk to them as well.
> 
> Also, if you can recommend a PV installer who covers the Costa del Sol area and who you have genuinely good experience with, please let me know either in the forum (if the rules allow that) or by sending me a PM.
> 
> Thank you.


That seems like a LOT of panels that some of the companies are recommending. Is your house very big and are you planning on having central heating/cooling running 24/7? That's the only way I could imagine you needing 22 panels!

We have nine 450 panels (installed in June) for a 180m2 house. We don't have central air, and we turn on the individual A/C units only in the rooms we're using - and not at all at night. But we don't hesitate to turn on the A/C (I live in Seville so the A/C goes on virtually every day), and there are 4 of us in the house so we often have multiple rooms being cooled at any one time. So far this summer with 9 panels we almost always produce more electricity than we need to cover our total daily usage. By the way, our usage includes an all electric kitchen and numerous computers and TV's running pretty much all day, but no pool. 

We have yet to see how it goes in the winter with less sun and running heaters.

In our case we don't have a battery so we lose the excess electricity being produced at peak sun times and we have to buy what we need from the grid for off-peak sun times. So I can't comment on the recommendations they've made for you about batteries.


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## sadlybroke

Thanks for your response. Our house is 220 m2 interior with central heating/cooling (which can be set up or switched on/off individually in each room), pool, home office, plus we plan for two electric cars in the future. We had an electric car in the UK up until last month and will definitely get another one as soon as we can.


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## Jamglish

sadlybroke said:


> Thanks for your response. Our house is 220 m2 interior with central heating/cooling (which can be set up or switched on/off individually in each room), pool, home office, plus we plan for two electric cars in the future. We had an electric car in the UK up until last month and will definitely get another one as soon as we can.


It does seem like a lot of power. With 14 to 22 450 Watt panels, you are looking at about 6-10 kW peak for a 220 m2 house. Our system has 6 450 Watt panels (2.7 kW peak) for 135 m2 and, probably because of roof angle and direction, we have yet to reach more than 2.2kW peak power. However, this summer during the daytime, the system provides for the pool pump (about 800 Watts, and cooling for either the living room or a couple of bedrooms, with some power still going back to the grid and some being bought no matter how I try to match the power consumption with the power generation. If you do plan on heating/cooling the whole house at the same time, and charging 10-15 kW Hr of battery storage, you will probably need all the power from the systems you are looking. But, you could probably be comfortable with a smaller system. We dont (yet) have any battery storage, but maybe it wouldnt be economical anyway if we relied only on surplus electric power from the panels to recharge the batteries. I am expecting that when we eventually replace the car with an electric one, it will be used to provide the battery storage. My 2 cents worth.


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## Alcalaina

kalohi said:


> That seems like a LOT of panels that some of the companies are recommending. Is your house very big and are you planning on having central heating/cooling running 24/7? That's the only way I could imagine you needing 22 panels!
> 
> We have nine 450 panels (installed in June) for a 180m2 house. We don't have central air, and we turn on the individual A/C units only in the rooms we're using - and not at all at night. But we don't hesitate to turn on the A/C (I live in Seville so the A/C goes on virtually every day), and there are 4 of us in the house so we often have multiple rooms being cooled at any one time. So far this summer with 9 panels we almost always produce more electricity than we need to cover our total daily usage. By the way, our usage includes an all electric kitchen and numerous computers and TV's running pretty much all day, but no pool.
> 
> We have yet to see how it goes in the winter with less sun and running heaters.
> 
> In our case we don't have a battery so we lose the excess electricity being produced at peak sun times and we have to buy what we need from the grid for off-peak sun times. So I can't comment on the recommendations they've made for you about batteries.


We are similar, eight 450kW panels for a 170m2 house, no battery. It's what the local installers recommended and it meets our needs quite adequately. I imagine prices have gone up since we bought ours nearly a year ago but I recommend you shop around!


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## dancingspider

Spotted this, this morning...

Quantum battery breakthrough paves way for instant recharging

Also heard of a woman who tried to flog her 5 year old electric car to various dealerships and the depreciation in value was horrendous!


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## sadlybroke

dancingspider said:


> Also heard of a woman who tried to flog her 5 year old electric car to various dealerships and the depreciation in value was horrendous!


Well, we sold our 6-year-old BMW i3 after a year of ownership for £1,500 more than what we had paid for it. I know the market has changed recently but from my experience, there is a huge interest in second-hand electric cars in the UK right now. I don't know the situation in Spain though.

I know several people with electric cars and no one would go back to an ICE car. The only people who regrettably buy an ICE car after owning an EV (like me) are those who need a large car (we have 3 kids and a big dog). At the moment there aren't many affordable large EVs out there.


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## sadlybroke

Is anyone using virtual batteries? Apparently, several companies in Spain have popped up recently that offer this. They are not really batteries, they are more like 'wallets' or brokers. They buy your surplus energy, take a cut and then let you use the "savings" that you have accumulated when you need it - either at night, during spells of bad weather or in winter. 

I have been talking with 3 PV panels installers in Malaga. One of them (a German company) does not recommend installing traditional batteries but totally recommends the virtual battery solution. However, another one says the cut these companies take is too high.

It seems it makes sense to install a lot of panels as they are relatively cheap and produce a lot of surplus electricity, then get your own batteries which are relatively expensive and are of no use for reusing the generated energy in the winter.

I am aware of the limit of 10kW panels installation before it becomes a project. We're thinking of installing a 10kW system (22 panels).

What are your thoughts?


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## olivefarmer

Dont understand “ batteries are of no use for reusing………” 

we are still in the learning mode. For example in the morning after a night of using the physical batteries till they are at a preset threshold, when we go to grid, in the morning the preset is charge the batteries. In practice this means that both the grid and the panels are in use until maybe 10 when the panels do all the work ( house and charge batteries) . It is a minor niggle.


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## Spanish Expat

sadlybroke said:


> Is anyone using virtual batteries? Apparently, several companies in Spain have popped up recently that offer this. They are not really batteries, they are more like 'wallets' or brokers. They buy your surplus energy, take a cut and then let you use the "savings" that you have accumulated when you need it - either at night, during spells of bad weather or in winter.
> 
> I have been talking with 3 PV panels installers in Malaga. One of them (a German company) does not recommend installing traditional batteries but totally recommends the virtual battery solution. However, another one says the cut these companies take is too high.
> 
> It seems it makes sense to install a lot of panels as they are relatively cheap and produce a lot of surplus electricity, then get your own batteries which are relatively expensive and are of no use for reusing the generated energy in the winter.
> 
> I am aware of the limit of 10kW panels installation before it becomes a project. We're thinking of installing a 10kW system (22 panels).
> 
> What are your thoughts?


My situation isn't identical (e.g., further north than you - near Madrid, and it's second home), but according to the numbers I crunched:

1) Makes sense (i.e, highest IRR) to install around 100% of annual consumption.

2) Return still positive but declines substantially if I produce beyond that. The recent introduction of "virtual" batteries offered by Próxima and others improves the economics here somewhat as they pay around 0.13€/kWh rather than the official 0.05€/kWh rate (and allow you to use surplus to offset capacity charge and over time), but they also charge relatively high rates for consumption. Return also declines because the 3 eligible subsidies (city, region and state) are capped.

3) Physical batteries don't make sense (high cost, short expected life), unless you're a "prepper" who wants to live off-grid.


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## Megsmum

Spanish Expat said:


> My situation isn't identical (e.g., further north than you - near Madrid, and it's second home), but according to the numbers I crunched:
> 
> 1) Makes sense (i.e, highest IRR) to install around 100% of annual consumption.
> 
> 2) Return still positive but declines substantially if I produce beyond that. The recent introduction of "virtual" batteries offered by Próxima and others improves the economics here somewhat as they pay around 0.13€/kWh rather than the official 0.05€/kWh rate (and allow you to use surplus to offset capacity charge and over time), but they also charge relatively high rates for consumption. Return also declines because the 3 eligible subsidies (city, region and state) are capped.
> 
> 3) Physical batteries don't make sense (high cost, short expected life), unless you're a "prepper" who wants to live off-grid.



You think only preppers live off grid?


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## dancingspider

If I was buying a house and wanted to live in Spain off-grid, i would buy a property with a river running thru it somewhere in the north of Spain (where it rains so much, it really feels like home) and create a mini hydro electric dam.

But just thinking about it, the Spanish are so bureaucratic, that putting a dam on a small river or stream would raise such a mountain of paperwork, in the end you would end up losing your marbles.


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## Jamglish

Finally received my first bill (September) that includes the compensation I received for the energy returned to the grid. The price I paid and the price I received for energy was not much different for the three daily time periods. I have a 100% renewable tariff with the price determined by the market, and maybe I am paying a bit over the odds for this. I don’t know, but anyway my system showed that I generated 323kW-Hr and directly used 231kW-Hr of this (72%), while my total energy use was 429kW-Hr. During at least part of the month I was running the air conditioner, pool pump etc. to try and use up the solar energy rather than return it. Anyway, the solar system figured I had bought 197kW-Hr and sent 92kW-Hr back to the grid, whereas the actual bill showed that I had bought 180kw-Hr and sent 72kW-Hr back to the grid. The bill is therefore about 20kW-Hr lower for both. Not a big difference, but I don’t know why. Anyway, in the end I received an average of 14.3 centimos per kW-Hr, for a total of 10.3 euros off our bill. This is better than the 5-6 centimos per kW-Hr I was expecting as compensation. Meanwhile, next month will mark a complete year since the system was installed.


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## Jamglish

dancingspider said:


> If I was buying a house and wanted to live in Spain off-grid, i would buy a property with a river running thru it somewhere in the north of Spain (where it rains so much, it really feels like home) and create a mini hydro electric dam.
> 
> But just thinking about it, the Spanish are so bureaucratic, that putting a dam on a small river or stream would raise such a mountain of paperwork, in the end you would end up losing your marbles.


I think damming a stream anywhere in a regulated country, including Spain, would require a raft of bureaucracy. The power you could generate depends on both the flow rate and the head (pressure). I am no expert on micro-hydro, but maybe it could compete in an area with slopes and a rainy climate, where solar is limited.


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## dancingspider

Jamglish said:


> I think damming a stream anywhere in a regulated country, including Spain, would require a raft of bureaucracy. The power you could generate depends on both the flow rate and the head (pressure). I am no expert on micro-hydro, but maybe it could compete in an area with slopes and a rainy climate, where solar is limited.


Did a quick check on the topic and you can get some tube type generators that you can simply immerse in a stream or small river. I would imagine no planning is required for that.

However, seems actually creating a dam would create a shed load of bureaucracy, that you simply would have to wade your way thru.

Hydro has to be lots better than solar, you get production in the evening, when solar cuts during the shorter days when you have peak energy demands in the evening and night.

No need to have to worry about batteries, unless you feel the need to add them.

Seems to me if you want to live off grid, buy a property with a small stream or river running thru it.

I imagine you could only dam a river if you lived out in the sticks, as you would never be granted permission if in a built up area.

Seem to be lots of calculators out there which tell you the power output based on flow rate and drop.


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## Jamglish

We have now had our panels for one year, and every day I have recorded the electrical energy generated, directly used, total consumption, sent back to the grid, and bought from the supplier. The panels are mounted on two sections of roof, neither of which are at the ideal orientation and angle. They have a total peak power production of 2.7 kWatts, but we have never actually hit the peak, with the most being 2.2 kWatts. We have also recently finally been actually compensated for what we send back to the grid. Here are some brief statistics.

We generated a total of 3300 kW-Hr. I estimate the maximum we could have generated if every single day was sunny and clear would have been 3820 kW-Hr. I was pretty diligent in trying to use all the power generated, and in the end directly used 2070 kW-Hr, or 63%. The energy sent back to the grid (uncompensated for most of the year) was 1230 kW-Hr. The total energy used was 4400 kW-Hr. This was more than I would have used if I had to buy all the energy. In summer, rather than moderate the use of daytime air conditioning, we ran it as long as there was sufficient energy being generated, with the temperature set lower than I would normally do. The maximum daily energy we generated was 14.7 kWatt-Hr. Use it or lose it!. If I had battery storage, I would revert to a more normal practice and store the excess rather than burn through it, and then use the stored energy at night time for more air conditioning or whatever rather than buying the energy. Storage of some kind (batteries, virtual, or electric car) would have reduced what we had to buy or sell back to the grid. We also have a solar water heater which helps reduce energy use.

Our energy supplier uses 100% renewable sources, and there is not much difference in price between the 3 daily periods. The compensation price for energy sent back to the grid is also divided into the same 3 periods. On our most recent bill, for October, we paid an average price of 0.25/kWatt-hr and received an average 0.13/kW-Hr for energy sent back to the grid. The month before, September, the values were 0.35 and 0.14 for energy bought and returned. I have no idea how these prices are determined.

The payback period for the panels is a moving target depending on the price paid and price received for electrical power. Regardless, there is no doubt that the panels have contributed to our quality of life by taking a good size chunk out of our electric bill and by allowing us to use electricity more freely, such as to run air conditioning in summer.


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