Solar Panel Heat

[kccwoodworks]

I am wondering how much heat is generated from the bottom of solar panels? Is it enough to use as a solar water heater by stringing black pipe under the panels? A few years ago I made a solar heater for a friends pool that circulated 300 gallons of 140 degree water twice a day in his pool. If solar panel generate enough heat it would reduce propane use and add to boondocking time. Thanks, Kurt

[wa_desert_rat]

Solar panels are dark and don't "generate" heat as much as become hot from the sunlight. You would be counting on heat transfer between the bottom of a panel mounted on stand-offs and the solar heater.

 

I have two Unisolar 69-watt "peel-and-stick" panels and two solid 240-watt panels on my rooftop. When I point a Harbor Freight laser heat sensor at the inside of the roof I can tell where the glued-down panels are (hottest), where there are no panels (cooler), where the standoff-mounted solid panels are (coolest).

 

But I don't think you could put a "solar heater" under a solid panel and have it get as hot as it would get if it were in direct sunlight. After all, it's in the shade.

 

Craig

[skp51443]

You'd get some reasonably hot water, not as hot as directly using the sun for heat though. A side gain would be that your panels would be cooler and if you had an MPPT controller it would make a tiny bit more power.

 

Downside would be more thermal stress on your panels as your cold water hit the back of them unevenly.

 

I'd guess it would be a fun project but not really practical.