Accelerated degradation by mechanical load of HIT solar cells encapsulated in flexible plastic

The degradation of plastic-encapsulated silicon HIT solar cells (156 × 156 mm²) with Ag and Cu metallization  was studied under mechanical load with a soft rod with a radius of 25 mm (Ball-on-Ring) up to a maximum 400 kPa. Local 2D photo- and electroluminescence, as well as measurements of dark and light current-voltage characteristics were used. Three phases were detected: (1) an increase in power by 2 – 4 % due to a decrease in leakage currents with pressures up to 125 kPa, (2) accumulation of deformations completed by the avalanche-like formation of a volumetric defect in the substrate with a radius of up to 10 µm with a drop in power by 3 – 5 %, (3) formation of a system of cracks with a width of < 1 µm, with an increase in their total length during under maximum mechanical load to 4000 ÷ 4100 mm and a decrease in of solar cell power to 12 ÷ 16 %.