Here you go Stephen, install a "boiler panel" on your rooftop to run this Scroll Expander Engine, which will be under that putative photo-voltaic miracle. You can run an ethanol-water antifreeze through the "boiler panel" and store the heat in insulated water tanks containing the propane "boiler pipes". Thus you don't need to buy $storage Batteries that run 15 watt-hours per pound at best.
The Mitsubishi FX105V scroll compressor used as an expander motor on Propane with 110 deg F (204 PSIG) rejecting into 70 F (110 PSIG). Cheaper than the online $256.00 refurbished price, at an Auto-Recycler's yard. A QUICK EXPERIMENT: Two 5 gallon (20 LB) Propane bottles, One in 120 F water, the other in cooler water and the expander in the gas stream. Reverse the bottle hose connections until you can find a cheap condensate return pump. An automotive electric fuel pump can get up to 100 PSI. Since it already has a pulley and clutch on the front end, getting some numbers on power output shouldn't be too difficult. http://www.engineeringtoolbox.com/propane-vapor-pressure-d_1020.html Photo: Disassembled Mitsubishi FX105V automotive AC compressor. http://www.redrok.com/images/fx105vsc.jpg Fred
