Hi We live in Provence in the south of France. With luck we should be starting a new build in 2010. We have a great deal of sunshine throughout the year (300 days plus)with cold winters....sub zero for a couple of months. What advice could you give me re underfloor heating via solar panels, or is this a bad idea and if so what method would you recommend. Thanks in anticipation.

It's a great idea but you'll have to find a loacl contractor to help you through it. With a new build you could consider the water storage area needed and it's not hard or even very expensive. You'd use a big tub of water and warm that water with the solar and then draw the heat out of the water and into the floors. You'd use a hot water heater as your backup.

My friend born and raised in Germany built a 3,000 sq-ft house and he used in floor heating and he has only one large resedential water heater which heats the house and makes hot water. It is set up such that the cold water in the summer that goes to the hot water heater is warmed by traveling through the house floors and it also cools the hose a little. It's a great system and if he didn't live under trees he'd be able to add solar. He told me this is common in Germany. We are in NE US where it's colder.

With good insulation everywhere you really can bring your costs way down.

Hi Jongig
Thanks for your reply.
That's the way i imagined it. However my real problem is whether to go solar or ground heat pump. i thought i would receive a great deal of advice on this forum but, as you can see very little forthcoming. I am aware that this is a US site, so maybe the membership doesn't encompass Europe.
Thanks again Jongig.
Regards W

The problem isn't so much a US/European divide, as it is the broadness of the question, with so little detail about the structure you're trying to heat or the technical resources available to you.

Active (pumped hot water) solar heating can work in most of France, and low temperature under-floor is ideal if that is your goal, but it's likely to be more expensive to build than ground source heat pumps.

But designing for passive solar (direct heating), and low air leakage super-insulated structures (the Passivhaus Institut approach) might be more cost-effective in moderate climates with good sun.

See: http://www.passiv.de/  Designing a Passivhaus for warmer-sunnier Provence is probably simpler/easier than for Germany & Austria. 

The weather in Provence is very similar to that of northern California in the US.  There is one Passivhaus  in Berkeley, CA that has gotten some press:

http://abclocal.go.com/kgo/story?section=news/drive_to_discover&id=6532082


http://www.dailycal.org/article/103788/home_appliances_help_to_heat_local_passive_house_

The details that make it work aren't very expensive or difficult compared to what it takes in colder climates:

http://www.nabihtahanarchitect.com/show_content.php?sid=24

http://www.nabihtahanarchitect.com/rte/upload/download/hem_nd08_tahan_remodel.pdf

It could be that simple for you too.  (Berkeley CA is only ~3C warmer on average than Aix en Provence in January.)

When you consider the complexity & cost of either active solar or ground source heat pumps, it may may more sense to go Passivhaus with a bit of passive solar.  If it turns out the difference in cost between a house that needs no heating system vs. a house with a very efficient heating system is less than  €5000, the maintenance, reliability, and operating cost of insulation and ventilation control is much lower than solar or ground source heat pumps.

BTW: Wilko isn't a very common French name (ben je nederlands of vlaams, mischien?)

I don't think it matters that you're in the south of France and I will gladly come help you because I'd love to go to france. My last name is Giguere which is French Canadian and I even took French in school. Can't remember a thing.

I think I'd always start with Geothermal and if the budget exists move onto Solar. You can't rely on Solar but you can with GT.

John