Albedo effects from using black solar panels

I have some questions regarding use of the recently announced new cheap solar power panels.

As background, the announcement of low cost solar cells is exciting because it looks like it could economically make direct conversion of sunlight into electrical power, mounted on roofs of homes and vehicles .. I feel very eager to get some of this cheap solar foil on the roof of my desert home for $2/W local electrical power supply. And, for SPS, the low implied mass of aluminum-foil backed solar cells would be more easily lofted into space by conventional launch vehicles, improving the economics of such ventures to some extent. In fact, solar panels competitive with coal burning power plants would at first seem to make the need for SPS obsolete.

However, there are some tough questions which include environmental system effects when used on the ground so as to prevent need of SPS to produce CO2-free electrical power; and structural stabilization of large foil structures in orbit, and orientation of that foil toward the Sun while also aiming millimeter-wave tight beams at specific rectenna sites on the Earth's surface, ever moving targets, much worse if the SPS is not in GEO.

The average albedo of a desert city changes when its light colored structures are changed to the dark color of solar panel material. Its air conditioning power needs become worse in the summer, already stifling when the wind is not blowing. Of that heralded incoming 277.8 W/sqft which had previously gotten mostly bounced back into space by light colored roofs and walls, now is getting absorbed and converted into structural and local atmospheric heat. And just when it is least welcome; Los Angeles area brownouts already happen in these conditions, what if the city is now largely blackened by the huge amounts of solar panels needed to power residences and businesses and most of all transportation? Even the light colored concrete pavement gets too hot to touch with bare skin, what happens when roof and wall surfaces are now solar panel colored black as asphalt but now also on walls and roofs big time? A square foot of black roof solar panel that is producing say 10% electrical energy from an increased energy influx of say 150W/sqft to run an air conditioner, is having to use its generated 15W to get rid of the 135W heat load added by the panel to the roof. That added 135W/sqft eventually has to heat the surrounding air, which is where the problem came from in the first place. When wind comes along, it just blows the heat problem next door, and it is a crowded city.

Looking again at a somewhat larger picture, when the Pop-Sci article quoted 277.8W/sqft solar influx is considered for that $2/Watt figure, are we again forgetting to consider that things cut into that influx big time here on the ground, things like nightime's darkness daily, cloudy weather, and latitude's slope and season's changing slope? Figures used to be stated like on average only 1/7 to 1/10 of that solar energy influx can be gathered on the ground. Large scale energy storage needs to provide load leveling, and individual homes might be able to utilize flywheel energy storage; nature stores some of that energy that we can tap off as hydroelectric power, wind and wave motion of course. Solar Power Satellites in GEO were conceived so as to provide that load leveling and efficient solar power collection up there where that 277.8W/sqft actually is continuously received.

Much lower satellites in LEO also have the Earth shading the satellite's solar collectors every once around; and they would be able to zap rectennas only intermittently as they pass by in low orbits. The aiming of the low orbit SPS would probably need phased array antennas (how power efficient are the drivers for the phased array antennas?) to track the rectennas it beams to during its "daytime" each orbit; GPS-like fleets of such orbiting power sats might be able to coordinate their energy beams to rectennas scattered around the planet, yet their beam angle variation and relative phase problems if receiving more than one sat's transmission would cancel out the other's energy to some extent.

Large foil structures in orbit likely need to be spin-stretched and structurally stabilized, and the gyroscopic action maintaining orientation toward the Sun is helpful; but if in low orbit, how is the ever changing angle of the beam toward the earth surface rectennas and the equally rotating transmitting antenna dealt with, including phase angle? A rectenna on the ground can be optimized for aim at the antenna fixed in position in GEO, that was part of the beauty of the original SPS in GEO concept.

The new low cost foil solar panel material might be best used in solar panel "farms" to augment wind farms and wave and tidal action energy extraction systems, but large scale blackening of already hot desert cities may not be wise in the larger picture. Even large desert areas now black with solar panels will add a huge warming effect to the planetary atmosphere; like stated in above example, at 10% conversion efficiency, the new solar panel adds 135 Watts of heat load to the planet for every 15 Watts of electrical energy it provides the electric power system. This is not CO2 greenhouse effect, but has a similar quality. So there are tradeoffs involved in use of these great new low cost solar panels.

To deal with the big picture for energy to power civilization, it still looks to me like we still need abundant SPS in GEO built as soon as possible to power civilization cleanly; and that means we need far more efficient transportation ways than rockets to build and maintain them up there in GEO (a subject which I have written about extensively, of course, see for references.)

Yet, along with the use of intelligently placed low cost new solar panels on the ground, it still seems useful to use rockets to lift materials to build small scale SPS in LEO to gain experience with some facets of SPS technology, and the availability of low mass solar panels that can withstand the space environment ought to make that more possible.


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