Temperature Dependent Quantum Efficiencies in Multicrystalline Silicon Solar Cells

Several field studies comparing modules based on Elkem Solar Silicon® (ESS®) cells with reference modules based on non-compensated virgin polysilicon show that the compensated ESS®modules outperform the reference modules with comparable installed capacity under certain operating conditions. At high temperatures and high irradiation conditions the modules based on compensated silicon produce more energy than the reference modules. In order to increase the understanding of the observed effect cells are studied at different temperatures by the means of IV-characteristics as well as quantum efficiencies. Quantum efficiency measurements show that the main difference between ESS®cells and polysilicon cells when increasing the temperature occurs in the 800 nm to 1100 nm wavelength range. Changes in this wavelength region are typically attributed the bulk properties of the material, i.e. the minority carrier lifetime and the carrier mobility.