The three physical modules and their main interconnections that rule the behaviour of solar cells under real operating conditions. Solar absorption and radiative heat exchange with the atmosphere govern the photogeneration of charge carriers as well as radiative cooling, thus requiring a very broadband optical calculation. Heat generation in the solar cell is the result of self-heating mechanisms (Joule, Peltier, Thomson effect, non-radiative recombinations, thermalisation) as well as solar absorption in non-active regions.The temperature-dependent optical and electrical properties introduce an additional coupling between the different physics.