METAL GRID OPTIMIZATION OF C-SI SOLAR CELLS FOR CONCENTRATING SYSTEMS

摘要

In the present work we have investigated the influence of metal grid on the cell performance of c-Si devices at one sun and under concentrated light. We have performed the modelling of the ohmic losses and different solar cells were realized by using metal grids having similar shadowing but different width and spacing between fingers. The first one was restricted to the lower values technologically feasible considering the future industrialisation of this process, namely transferring the concentration solar cell technology from lab-scale to pre-pilot level. The finger spacing was calculated and selected bearing in mind low shadowing and by taking into account the chosen finger width and height. The very high current level of this kind of devices imposed the use of thick fingers/busbar on the contacting structure in order to reduce the ohmic losses. We made a comparative study of the electrical behaviour of different devices (current-voltage and quantum efficiency characterization) at one sun and under concentrated light, to investigate the influence of different metal grid on the electrical performances of the devices. The best cell realized in our laboratory achieved the efficiency of more than 19.5% at 1 sun, 20.5% at 100 suns and more than 19% at 160 suns.