They just profiled that roofing material on HGTV recently. They did mention the price and it was very high, but I can't recall what it was. Why not geothermal heating for water?
We looked into geothermal, but it was hideously expensive. Now that could be because we're in MA, I don't know. We hope to move back South, so that's where all this will take place, someday.
I'll have to look on the HGTV website to see if they have a link to the roofing you saw.