4 ms·

I think generally the opposite, as the panels absorb much more overall light than the ground generally does. They're by design as close to "black" as possible s

I think generally the opposite, as the panels absorb much more overall light than the ground generally does. They're by design as close to "black" as possible since the goal is to capture light and not reflect any. Of course, a hot spot also causes updrafts, so your thought there is still valid. Personally, I think combining solar PV with solar thermal is an interesting option. When your panels are often seeing temperatures in excess of 90C (that part I am confident is true), it seems like using a heat exchange fluid to both cool the panels (improving efficiency and lifetime) and deliver that heat to a heat engine or use as a preheater for a steam generation system is interesting. I think possibly more interesting for residential, where a 90C heat source preheating your residential water before your water heater could significantly increase the effective efficiency of your panels. You generate high value electricity from as much light power as you can, and use the waste heat to decrease your use of electricity/gas for heating. Win-win, and the cost is just some heat exchangers and tubing.

stuki 13y ago
I like that thought. Assuming the heat exchange plumbing and attendant sensors could be made efficient and reliable enough to be relied on, the ability of panel designers to optimize their panels for operation in a tighter temperature band, should allow for improved efficiency of primary generation as well. Sounds like this mega plant is designed with a fair amount of redundant capacity; for cloudy days, maintenance etc. If so, this may facilitate "real world scale" testing of approaches like yours without unduly affecting "production."
jdmichal 13y ago
90°C is not really hot enough to extract efficiently. The Carnot cycle efficiency of such a process, even assuming it used a cold-sink at 0°C (not likely), is only 25%. However, using that warmed water as a preheat for another process is perfectly valid.
- neltnerb 12y ago
  Yeah, that's my thought. Think heat exchanger, not heat engine. If you managed to get your input water at 10C from the ground up to 30C, you'd have very little left to do before it's usable in a shower. Either way, the thermal mass of the flowing cool water will definitely improve the solar PV efficiency and lifetime.

stuki 13y ago

I like that thought. Assuming the heat exchange plumbing and attendant sensors could be made efficient and reliable enough to be relied on, the ability of panel designers to optimize their panels for operation in a tighter temperature band, should allow for improved efficiency of primary generation as well. Sounds like this mega plant is designed with a fair amount of redundant capacity; for cloudy days, maintenance etc. If so, this may facilitate "real world scale" testing of approaches like yours without unduly affecting "production."

jdmichal 13y ago

90°C is not really hot enough to extract efficiently. The Carnot cycle efficiency of such a process, even assuming it used a cold-sink at 0°C (not likely), is only 25%. However, using that warmed water as a preheat for another process is perfectly valid.

neltnerb 12y ago
Yeah, that's my thought. Think heat exchanger, not heat engine. If you managed to get your input water at 10C from the ground up to 30C, you'd have very little left to do before it's usable in a shower. Either way, the thermal mass of the flowing cool water will definitely improve the solar PV efficiency and lifetime.