When RPVSPs are installed on roofs, they absorb a significant amount of solar energy, converting some of it into electricity but also generating heat in the process. This heat is released into the surrounding air, leading to an increase in air temperature around the panels. Moreover, the elevated installation of RPVSP creates two hot surfaces: the top surface of the panels and the underside surface. As air flows over these RPVSPs, it picks up heat more efficiently than it would from typical building or ground surfaces. Observational studies in the literature have shown that areas with RPVSP arrays can experience higher daytime air temperatures compared with reference sites without RPVSP.
In essence, the heat that would be absorbed by the building (requiring more energy for cooling the interior) is instead absorbed by the panels and conducted to the surrounding air which creates a convective heat exchange cycle on a city wide scale. It would be interesting if this were compared to awnings (and pegodas) that have been in use for centuries for passive cooling of space in and around buildings.
Further, It seems like this would call for the use of phase changing material to absorb the heat from the back of the solar panels which would reduce this intensification of the urban heat island effect as the heat energy would be use in the phase change process during the day and slowly released in the reverse phase change at night without conducting more heat into the building.
None of this seems to have any real consequence on the global warming effects of greenhouse gasses (primarily natural gas [methane] and Carbon Dioxide). But it is a more accute concern that is more likely to be addressed through local ordinances, laws, and regulations.
this would call for the use of phase changing material to absorb the heat from the back of the solar panels
There are quite a few “better” technologies for cooling solar panels, which happens to also improve their efficiency/production.
Thermoelectric devices would boost production a little, and keep production a bit past end of day. This might not yet be cost effective, but massive production scale could change that. Circulating water behind the panels, transfers the most heat, and hot water is useful to everyone. A simpler, leak proof, technology is to suck in air behind/under the panels that creates a flow that will cool them, and use that hotter air to feed a heat pump.
Also, the paper casually mentions how rooftop solar reduces the cooling load of the building. What I didn’t see acknowledged was that that extra cooling load (presumably traditional A/C) on a building without rooftop solar moves the heat out of the building into… (drum roll), the surrounding environment. So… the heat still got to the surrounding environment, it just took a longer path to get there.
The theoretical explanation:
In essence, the heat that would be absorbed by the building (requiring more energy for cooling the interior) is instead absorbed by the panels and conducted to the surrounding air which creates a convective heat exchange cycle on a city wide scale. It would be interesting if this were compared to awnings (and pegodas) that have been in use for centuries for passive cooling of space in and around buildings.
Further, It seems like this would call for the use of phase changing material to absorb the heat from the back of the solar panels which would reduce this intensification of the urban heat island effect as the heat energy would be use in the phase change process during the day and slowly released in the reverse phase change at night without conducting more heat into the building.
None of this seems to have any real consequence on the global warming effects of greenhouse gasses (primarily natural gas [methane] and Carbon Dioxide). But it is a more accute concern that is more likely to be addressed through local ordinances, laws, and regulations.
There are quite a few “better” technologies for cooling solar panels, which happens to also improve their efficiency/production.
Thermoelectric devices would boost production a little, and keep production a bit past end of day. This might not yet be cost effective, but massive production scale could change that. Circulating water behind the panels, transfers the most heat, and hot water is useful to everyone. A simpler, leak proof, technology is to suck in air behind/under the panels that creates a flow that will cool them, and use that hotter air to feed a heat pump.
Those all seems like very workable options.
Also, the paper casually mentions how rooftop solar reduces the cooling load of the building. What I didn’t see acknowledged was that that extra cooling load (presumably traditional A/C) on a building without rooftop solar moves the heat out of the building into… (drum roll), the surrounding environment. So… the heat still got to the surrounding environment, it just took a longer path to get there.