By reducing the contact resistance at the electrode, Mitsubishi Electric has increased the cell conversion efficiencies of its polycrystalline silicon wafers to 19.3%. Confirmed by the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, the cell (15 cm x 15 cm x 200 micrometers) is 0.2 points higher than the company’s previous record of 19.1%. The company also reported an ultrathin polycrystalline silicon PV cell (15 cm x 15 cm x 100 micrometers) reached efficiencies of 18.1%, a 0.7-point improvement over the company’s previous record of 17.4%, also verified by AIST.
Mitsubishi’s approach to resistive loss uses a treatment to the wafer prior to electrode formation to improve electrical contact performance. The company said that this reduced resistive loss by 4% compared to previous PV cells.
The 0.2-point improvement over the previous record of 19.1% enables the electrical output in a cell of practical measurements to increase by approximately 1%, from 4.16W to 4.2W.
The new performance results were obtained with the integration of previously developed technology, such as a low-reflection, honeycomb-textured surfacing process that reduces sunlight loss caused by reflection and a reflective structure for the rear surfaces of the cell.