Science & TechFact
Why solar cells can never use 100 percent of the light.
A silicon cell only uses photons with energy above its band gap; red and infrared photons are wasted. Blue photons carry too much energy, and the excess becomes heat. This gives the Shockley–Queisser limit: a single-junction cell can theoretically reach about 33 % at most. Commercial modules today sit at 20 to 23 %.
Useful: Tandem cells stack materials with different band gaps and exceed 40 % in the lab.
Source: en.wikipedia.org