DETERMINATION OF SOLAR-CELL DIFFUSION CAPACITANCE AND ITS DEPENDENCE ON TEMPERATURE AND 1 MEV ELECTRON FLUENCE LEVEL

A simple analytical method to determine the solar cell diffusion capacitance (C(d)) is presented. The dependence of C(d) on the cell operating voltage (V), the temperature (T) and the 1 MeV electron irradiation fluence level has been investigated for silicon solar cells. It is shown that C(d) increases exponentially with V. Hence, C(d) at open-circuit voltage (V(oc)) is at least an order of magnitude higher than at the cell maximum power point voltage (V(mp)). Furthermore, C(d) for a cell with back surface field (BSF) is about 6 times higher than for a non-BSF cell. C(d) decreases with T at V(oc), whereas it increases with T at V(mp). 1 MeV electron irradiation of the cell decreases C(d) and at higher fluence levels (almost-equal-to 1 X 10(15) 1-MeV e/cm2) C(d) is almost independent of BSF.