Would I receive more energy from a solar cell if I were to filter everything but UltraViolet light? Or do you get more energy from all wavelengths added together?

Asked by: Marc Bourque

Answer

A solar cell uses the photoelectric effect to create an energy imbalance within the cell which can be used to drive some load. Now, this effect requires that a certain amount of energy be present "per photon" in order to create this imbalance. If that amount of energy is not present, while electrons may be jolted a bit within the atoms they reside, no net imbalance will be created. So truly (in an ideal world) removing wavelengths of light that were not energetic enough to free an electron would not affect the load at all. In fact, even pummeling the solar cell with a great amplitude (many photons) of this light would not create the necessary imbalance. Higher frequency (that is, higher energy/higher momentum) photons are required in order to make the solar cell work. The lower energy ones simply do not contribute at all. However, physically realizable filters are not ideal. Not only will you not be able to cut out exactly all energy which is "too low" for the cell, but you may end up attenuating signals which are perfect for the cell. In reality, your output energy will probably be higher without the filter regardless of what you've done So no, you will not receive more energy by filtering. And lower frequency signals should not benefit the solar cell anyway.
Answered by: Ted Pavlic, Electrical Engineering Undergrad Student, Ohio St