S. Himmelstein | July 19, 2022
The incidence of crack and hot spot formation in solar cells is on the rise as photovoltaic wafer thickness wanes. The implications of these cracks for crystalline silicon-based solar cell performance were explored by researchers from the University of York, U.K.
Three-busbar solar cells with an open-circuit voltage of 0.61 V, a short circuit current density of 38.8 mA/cm2 and a peak power of 4.72 W were connected with a power supply for biasing purposes under short circuit conditions. The cells were submitted to solar illumination under varying irradiance up to 1000 W/m2 at a constant 25° C temperature. Analysis of data generated by electroluminescence imaging revealed the solar cells were affected by crack percentages ranging from 1% to 58%.
Thermal image taken at the end of the experiment of the three tested solar cell samples. Source: University of York/Scientific Reports/CC BY 4.0
The researchers explained that output power losses for the cells with crack percentages below 11% were insignificant. A crack percentage exceeding 46% is also insufficient to develop a hotspot, as there is a significant inactive area in the cells. Potential induced degradation was observed to result in 30% to 40% losses in the output power, the same amount of losses when a solar cell is affected by at least 25% cracks.
The results published in Scientific Reports confirm that small cracks have a negligible effect on solar cell output and induce no hotspot development.
