The quantum efficiency and photocurrent for AlGaAs quantum well solar cell is calculated and compared with experimental results obtaining good agreement. The conversion efficiency as a function of Al composition in barriers and wells is presented showing that there is a wide range of Al composition barrier and Al composition well where the QWSC efficiency is always higher than corresponding homogeneous p–i–n cell without quantum wells. We also show that for up to 15 wells in the intrinsic region an efficiency enhancement for the QWSC over the baseline cell is obtained.