# Why do solar panels have maximum efficiency? # Why do solar panels have maximum efficiency - Solar panels generate power when an electron in a semiconductor gets enough energy to jump to the conductive band. - This is a discrete transition. - Any photon with energy less than the band gap won’t create an electron-hole pair so all the energy in the low frequency end of the spectrum isn’t captured. - Additionally, any energy above the bandgap is wasted — even if a photon has 2+ bandgaps worth of energy, it will only create one electron-hole pair. - Also, not every photon is absorbed. Some either reflect or pass through the material. (Not many do the latter) - There’s various tricks people are trying to use to capture more energy — materials that absorb high-energy photons and emit multiple photons at lower energy; materials that can bump multiple electrons, etc. But at the end of the day, the efficiency comes from the quantum nature of the photon -> energized electron conversion. <!-- #questions/answered --> [Web URL for this note](http://notes.benjaminreinhardt.com/Why+do+solar+panels+have+maximum+efficiency) [Comment on this note](http://via.hypothes.is/http://notes.benjaminreinhardt.com/Why+do+solar+panels+have+maximum+efficiency) <!-- {BearID:D7BF28BE-9B7D-4AA2-B6DF-CAE2C29EE8AE-2401-00000D3367FF295A} -->