Finally, the charge carriers are extracted from the solar cells with electrical contacts so that
they can perform work in an external circuit (Fig.Thus, the maximal energy conversion efficiency of a single-junction solar cell
is considerably below the thermodynamic limit.This single bandgap limit was first calcu lated by Shockley and Queisser in 1961 [2These two mechan isms alone amount to the loss of about half the incident solar energy in the conversion
24 Solar Energy
process [26]. 3.2 ?).3.1 (b).