How do solar cells (photovoltaic cells) work? There are very simple explanations, but you can probably find a video with any level of complexity you might want.
This video from the U.S. Department of Energy is fairly general and makes a nice introduction:
This video adds some useful detail.
For even more detail, NASA’s page on photovoltaics is very good, and Scientific American has a neat little interview with Paul Alivisatos that goes into the parallel between photovoltaic technology and photosynthesis.
