I have an upcoming paper to write for my solar cells course. The question is something along the lines of, if we have a p-n junction which side should we shine the light on for efficiency? Should it shine on the p side or the n side? Efficiency at this point is defined loosely, and can range from anything to solar efficiency to financial. I need a baseline to compare my results. So I need to know what is used in the real world. I'm not asking for a reason why they are used that way. I'll figure this out myself. Any help would be great here. Even pointing me in the right direction would be nice. Thanks in advance.