# Solar Water Panels for Central Heating?



## ratzakli (May 20, 2012)

Hi again

Have any of you got your central heating supplied by solar water panels?

I was looking into this and it seems feasible. I know you can store the heated water in one of those thickly-insulated storage cylinders so that would allow you to use it at night time as well, but do you have enough to provide hot water and central heating? 

I'm not sure if they would get you through the whole winter, especially if you have periods where there are murky, sunless days. I guess you could just switch to electrically heating the cylinder for short periods.

Thanks

Stuart


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## ratzakli (May 20, 2012)

Forgot to mention - the other option I was looking at was ground source heat pumps. 

I have tried a few Google searches but there doesn't appear to be much information about them being used in Greece - apart from a few larger industrial properties. 

Also, these seem to be a lot more expensive to fit, although I don'[t know if they are any more efficient than other types of heat source.


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## Veronica (Apr 5, 2008)

Normal solar panels won't supply enough to run electricity and central heating. You probably mean Photo voltaic panels.


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## ratzakli (May 20, 2012)

From what I have seen so far, the cost to have enough PV panels installed would be far too great to make it worthwhile. 

Perhaps it might be worth thinking about having two sets of solar working side-by-side. One for domestic hot water and the other for most of the central heating. 

We would probably also want a wood-burning stove or fireplace anyway (as much for the aesthetics as for practical use) so that could take up any slack during the coldest days.


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## titania (Jan 3, 2013)

ratzakli said:


> Hi again
> 
> Have any of you got your central heating supplied by solar water panels?
> 
> ...


Hi, I might have half an answer for you.

At a time when I was too broke to buy a brand new heating boiler, replace the gas pipes and the old radiators, I had to find some way of heating my home. I live near the Alps in France, average low in winter is something around 0°c, meaning lows about -6-9°C and highs of about 5°C. House is large - 250 sqmts, old, uninsulated, with a huge veranda half insulated only.

I bought 5 electric water heaters (the cheapest, 140 euros each), circulating pumps (3 at 50 euros) and expansion tanks (2 at about 50 euros), wired the lot together with new cheap steel radiators (23 of them at about 35 euros each), plus rolls of PER piping.

I placed 2 heaters in the cellar, 2 on the first floor, 1 in the roof. Capacity was 250 liters and 200 liters. I managed to heat the house to 23°C, and the veranda to 19°C (5 radiators). Electricity bill was horrendous, but it got me through without having to replace the whole system. It was also one half cheaper than the renewable heat pump system which I had. These electric water heaters are very well insulated. You need to toy with the circulators speeds to achieve a balance. Having a night tariff for electricity would help.

Parallel to that, I had 2 solar panels on the roof, which were part of a renewable energy system that did not function. I managed to have them work with a special water heater for solar systems (500 liters) for the hot water in the house (showers, sinks, etc.). I could not connect the panels to my DIY system because I could not find a plumber willing to chance something really new; also because the hot water system was standardized as "drinking water" and I could not make the split between that and radiators water.

So, to your question. If you have diy capabilities or a friendly plumber, you could I think devise a system whereby you would have:

- solar panels for hot water for showers, baths, sinks etc. You can diy the solar panels easily, especially if you are in a zone without frost in Greece. The question of using evacuated tubes only arises really in very very cold climates. In Greece, probably any system that is not evacuated tubes would be efficient enough - Google is your friend.

- solar panels to produce hot water to fill electric water heaters during the day. You would string several electric water heaters like I did and have them filled with the solar hot water during the day. You would circulate the water in the radiators with circulating pumps (don't forget the expansion tanks too). At night, if the water cooled down too much, you could have the electricity kicking in to re-heat. Because I did not use the solar panels, I had to use electricity day and night, but in your case it would only be at night or on overcast days.

- supposing you had floor heating, then it would be better because you would not need to heat the water as much as for filling in radiators.

- you need to contemplate the costs of the electricity. Only you can do that. Take the power of each heater, number of hours per day, consumption and cost by kW.

- This year I was fortunate to be able to replace the system with a gas boiler with which I am happy. I have now reduced my heating bill to about 1/4 of what it was originally with the heat pump, or in other words, to about 1/2 of the electric water heaters.

The solar panels central heating combined with the electric water heaters is the solution I would contemplate when I move to either Portugal or Spain since many places do not have city gas. The guy who strung my 5 electric water heaters together is willing to do it for me in Portugal/Spain and this time he's willing to hook them to solar panels which I'll DIY myself - he'll get wages for the plumbing, free plane ticket and a free holiday with French food the Portuguese style 

Good luck and let us know what you choose.


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