Study on graphite paste for back contact of CdTe thin film solar cells and modules

Preparing ohmic back contact is one of key processes to develop efficient and low cost CdTe thin film solar cells. The doped graphite paste was used as back contact layer of CdTe thin film solar cells. The dependence of CdTe thin film solar cells characteristics on component and annealing process of graphite paste was studied. The results show that the efficiency of small area elementary CdTe solar cells can reach up to 10.2% by using graphite paste as back contact layer. But the efficiency of small area elementary CdTe solar cells without graphite back contact layer is only 3.8%. The optimized process was used to prepare large area CdTe thin film PV module, and the 27.0 cm × 36.7 cm CdTe PV cells module with efficiency 7.4% was successfully prepared.