If you could diffuse the spectrum, you could reflect the IR but absorb the UV.
Not being a physicist, I don't know what that would entail.
Not being a physicist, I don't know what that would entail.
"Solar cells are made out of N-type and P-type semiconductor material that use the visual light spectrum to generate electricity. Solar radiation with wavelengths of 380 nm to 750 nm (violet to red) strike the material with enough energy to knock electrons from their weak bonds and create an electric current. The unused wavelengths (ultraviolet & infrared) do not have enough energy to dislodge the electrons and are absorbed as heat."
So, I think this idea is pretty feasible if there is some sort of IR and UV filter that could reflect the IR and UV wavelengths at the heat collection tower and let the visible light into the PV cell to have multiple electricity generation sources. I would imagine doing that would more efficiently make use of all the light energy collected, rather than only the wavelengths that can transform the light energy into heat.
I don't know if something like that exists... I know there are UV and IR filters for cameras but I am not sure if by filter they reflect the IR and UV light and let only the visible spectrum through.
Physics states that (Reflection coefficient + Absorption coefficient + Transmission coefficient = 1), all wavelength dependent. Now if you want a high number for the reflectivity in IR, you will have a low number for the absorption coefficient.
If you have a low absorption coefficient you will most probably have a low emission coefficient since those two are linked (equal for black bodies, see Kirchhoff's Law/gray body).
So you have a low emission coefficient in the IR, and the thermal emission due to the heating from the absorbed UV will be quite inefficient, and thus there will be more heating, which is bad (edit: the heat will not be transported away and will accumulate).
Of course if you have good materials you might be able to migitate, but at first glance it looks problematic to me. Sorry for inelegant language.
Sunlight does not bring in a lot of IR, and almost all of that is absorbed in the upper layers of the atmosphere. What you have to consider then is ambient IR radiation from the surroundings due to thermal emission. The process is the same as the one we're assessing for the PVs, and the wavelengths are not too different. PVs are normally warmer than the surroundings due to their higher temperature, so less energy will be absorbed that radiated off in the IR.
Hm, maybe I misunderstood how you want to remove the IR? Let's consider some sort of reflectant shell around the PVs but not part of them. On the inside it would receive the heat from the PVs and of course, also reflect great parts of it back, letting it accumulate. We built an insulation. Not good. Maybe you can explain your idea in more detail?
The mechanism I discussed above is of course not the only relevant process, things like heat conduction and heat capacity of the material are also important.
In conclusion: Yes, there would be a net loss of incoming energy, but the mechanims that let energy be transported off might be severely hindered by our alteration. Thus, an accumulation of heat.
There might be ways to make it happen nevertheless, eg with water cooling, but it would require more infrastructure. (But then, I'm not an engineer..)
You could also just cool the cells and try to use the waste heat.
Actually in space you could have these gossamer structures more easily as there is more ...space, and the weight penalty is less. I know some satellites use primitive concentration methods coupled with very high efficiency cells to generate a lot of power.
If they're not doing this, there must be a good/obvious reason why not.