Loss analysis of back-contact back-junction thin-film monocrystalline silicon solar cells

We investigate the power losses in back-contact back-junction monocrystalline thin-film silicon solar cells. The cells are made from epitaxial layers grown on and separated from porous Si (PSI process). We combine two-dimensional finite element modeling with a resistance network simulation. The simulated and measured current-voltage characteristics agree. Free energy loss analysis reveals that the main limiting loss mechanism of the best cell with 13.5 % efficiency is the high saturation current density at the metal-silicon interface of 5×10⁴ fA cm², causing 2.5% absolute efficiency loss.