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.