In the thickness of a solar cell (semiconductor), photons will "strike" and be absorbed by all areas of the thickness. That means some in the N doped layer and some in the P doped layer of the semiconductor "sandwich". The center of the "sandwich" is where the depletion region exists. This is where the real energy is captured from a photon "strike" as the positive/negative charge separation will immediately migrate to the N doped & P doped sides. The rest of the photon strikes just "recombine" in the strictly N doped or P doped only layers.
Heat causes vibration (energy to the atoms). Thus, a phenomenon of "minority current carrier" increases. Minority current carrier increase will increase recombination & thus take away the normally photon absorbed/created "separated" useful charges. So effectively you can say that it takes less energy to excite the electrons (by photons), but the increased recombination of these electrons inside of the cell degrades its useful output.
One start-up company created a dual type solar cell that harnessed the solar cell heat using a backside electricity generating cell called a Peltier effect device. This system required a circulating fluid to transfer thermal energy to piping in the ground - acting as a heat pump system. The extra usable charge current from the Peltier device added to the overall output - while cooling the solar cell and keeping it in a more efficient operating range. Getting the costs down to a competitive product pricing range was their challenge.
“Thus, a phenomenon of “minority current carrier” increases. Minority current carrier increase will increase recombination & thus take away the normally photon absorbed/created “separated” useful charges.”
Thanks for the explanation. I figured minorities were somehow to blame! Everywhere you go they manage to screw things up! :)