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What I'm more interested in is passive cooling for solar panels. We lose so much efficiency from higher temps. Placing them on our hot roofs, even with an air g

by RenRav 7y ago

What I'm more interested in is passive cooling for solar panels. We lose so much efficiency from higher temps. Placing them on our hot roofs, even with an air gap, is just ridiculous.

Yetanfou 7y ago
Combine that passive cooling with a heat pump to create hot water from PV panel waste heat and you'll both gain efficiency as well as a hot water source.
- thinkcontext 7y ago
  Here's a DIYer that did that but instead of hot water used a minisplit https://renewablesystemstechnology.com/solar-heat-pump-system.html https://renewablesystemstechnology.com/solar-heat-pump-syste...
  - Yetanfou 7y ago
    Although a simpler solution to build due to the absence of liquid coolant I'd still choose a combination of PV-panels with liquid-based collectors attached to the back as this also makes it possible to circulate warm coolant through the collector to de-ice/snow the panels in wintertime.
throwaway5752 7y ago
How much efficiency do they lose? What else reduces efficiency, and is the trade off to moving them to a different location worse? On the first one: let's look at a high end model like https://www.energysage.com/solar-panels/sunpower-corporation/774/spr-e19-320/ https://www.energysage.com/solar-panels/sunpower-corporation.... You will see the temperature coefficient of PMax and Voc in the specs. The PMax in this case is -.38. You can predict a panel's loss of efficiency by multiplying the difference in degrees Celsius from standard testing conditions. Standard testing conditions for a solar panel is at 25 Celsius. A hot panel in summer will get up to 65 C. So 40 x -.38 in this case, or just a bit over a 15% loss. That is not great, but 85% of max efficiency is not ridiculous. Panel orientation, angle, and shading can easily add up to more than that. The second question is a much harder one. What's ridiculous is not having solar panels.
TaylorAlexander 7y ago
This is passive cooling for solar panels, basically. The title says its for cooling buildings but in reality they created a solar panel* with a cool bottom. It seems like they could thermally couple the two if they wanted. *The solar panel was not able to produce electricity.

by RenRav 7y ago

What I'm more interested in is passive cooling for solar panels. We lose so much efficiency from higher temps. Placing them on our hot roofs, even with an air gap, is just ridiculous.

Yetanfou 7y ago

Combine that passive cooling with a heat pump to create hot water from PV panel waste heat and you'll both gain efficiency as well as a hot water source.

thinkcontext 7y ago
Here's a DIYer that did that but instead of hot water used a minisplit https://renewablesystemstechnology.com/solar-heat-pump-system.html https://renewablesystemstechnology.com/solar-heat-pump-syste...
- Yetanfou 7y ago
  Although a simpler solution to build due to the absence of liquid coolant I'd still choose a combination of PV-panels with liquid-based collectors attached to the back as this also makes it possible to circulate warm coolant through the collector to de-ice/snow the panels in wintertime.

throwaway5752 7y ago

How much efficiency do they lose? What else reduces efficiency, and is the trade off to moving them to a different location worse? On the first one: let's look at a high end model like https://www.energysage.com/solar-panels/sunpower-corporation/774/spr-e19-320/ https://www.energysage.com/solar-panels/sunpower-corporation.... You will see the temperature coefficient of PMax and Voc in the specs. The PMax in this case is -.38. You can predict a panel's loss of efficiency by multiplying the difference in degrees Celsius from standard testing conditions. Standard testing conditions for a solar panel is at 25 Celsius. A hot panel in summer will get up to 65 C. So 40 x -.38 in this case, or just a bit over a 15% loss. That is not great, but 85% of max efficiency is not ridiculous. Panel orientation, angle, and shading can easily add up to more than that. The second question is a much harder one. What's ridiculous is not having solar panels.

TaylorAlexander 7y ago

This is passive cooling for solar panels, basically. The title says its for cooling buildings but in reality they created a solar panel* with a cool bottom. It seems like they could thermally couple the two if they wanted. *The solar panel was not able to produce electricity.