Auger recombination is a form of efficiency loss in a solar cell.
This process occurs when an electron recombines with a hole, and gives its energy to another electron which kicks it higher in the conduction band. The electron that was kicked higher quickly relaxes and falls into a lower energy level while giving off heat.
For this process to happen you need two electrons to be very close to each other (eg. a material that is heavily N-type doped). This recombination can be avoided by not having the semiconductor doping level be too high.