Einstein was awarded the Nobel Prize in Physics for his work on the photoelectric effect, not for his work on relativity. Little did one know that the same people who helped us calculate everything under the sun is also the same person helping to bring renewable solar energy to the masses.
The following article explains in varying levels of detail; how a solar cell converts sunlight energy into free electrons, which is called the photoelectric effect and how, from the physical perspective, the use of silicon moves electrons through various states to produce useful solar generated electricity.