A nice simple solar hot water heater. I have had some interest in this myself, but more so for heating a pool.
http://www.scienceprog.com/harvesting-energy-with-home-made-solar-thermal-collector/
A nice simple solar hot water heater. I have had some interest in this myself, but more so for heating a pool.
http://www.scienceprog.com/harvesting-energy-with-home-made-solar-thermal-collector/