Regarding the lighting setup for measuring the solar cells, I'm not sure I agree with all the dire warnings about getting the right color spectra, etc. After all, all the O.P. is trying to do is to separate good cells from bad. It doesn't matter if the light source they use isn't as close to sunlight as possible, so long as the light output is consistent so they're always comparing apples to apples.
In other words, once they characterize a known good cell, they can use those measurements to sort the rest of the cells.