Optimization of the back contact for 1.43 m2 a-Si:H photovoltaic module products based on the indoor light soaking test

• The metal back contact is optimized to couple with the ZnO:B back reflector for a-Si:H photovoltaic modules.
• The Ag/Al back contact leads to a severe degradation ratio of 24.2%.
• The light soaking test causes the partial delamination of the Ag back contact from the ZnO:B back reflector.
• The Al back contact leads to a higher stabilized aperture efficiency of 7.3% due to the lower degradation.
• Through the further optimization, the stabilized aperture efficiency of 7.4% is achieved.

We have investigated the optimization of the sputtered metal back contact coupled with the B-doped zinc oxide (ZnO:B) back reflector for 1.43 m2 p–i–n type hydrogenated amorphous silicon (a-Si:H) single-junction photovoltaic modules. The module with the Al back contact leads to the high stabilized aperture-area efficiency (ηAPER) of 7.3% with the low light-induced degradation ratio of 12.6% despite low initial ηAPER of 8.3%. However, the insertion of Ag causes a severe light-induced degradation. Through the further optimization, the stabilized maximum power of 100.2 W is achieved. This is corresponding to stabilized ηAPER of 7.4%, which is the highest value for the certified industrial products of 1.43 m2 a-Si:H single-junction photovoltaic modules.