Small cracks have a negligible effect on solar cell performance
cracks photovoltaic performance technology 2022
British researchers have found that crack rates of up to 11% have very limited impact on solar cell performance. They also found that problems are likely to occur when the crack percentage is between 11 and 34%.
Researchers from the University of York investigated how the performance and durability of solar cells it can be affected by different crack sizes and by the formation of foci.
They identified that their work is intended to fill a knowledge gap. Regarding whether all types of cracks can lead to a significant drop in the output energy production of solar cells. The cracking issue in solar cells gets worse as the panel thickness decreases, they said. This is because the reduced thickness makes it easier to develop additional mechanical stresses in the cells when they are assembled into a large-scale PV module.
Their analysis was conducted on solar cells of three series, provided by an anonymous manufacturer. With an open-circuit voltage of 0,61 V, a short-circuit current density of 38,8 mA/cm 2 and a maximum power of 4,72 W.
They used electroluminescence (EL) imaging via a 6 k × 4 k pixel digital camera and an 18–55 mm camera lens. The solar cell samples were connected to a power supply for bias purposes under short-circuit conditions, the scientists said. "Crack percentage was calculated by subtracting a cracked and uncracked image."
The UK team subjected the cells to sunlight under irradiance of 100-1000 W/m 2 and their temperature was held constant at 25 C. Through these measurements, they found that the solar cells were affected by cracking rates ranging from 1% to 58%.
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The researchers explained that output power losses for cells with crack rates below 11% were negligible. Adding that these hives are relatively equivalent to uncracked hives. It is recognized that a point is about to develop if the crack percentage, which essentially represents an inactive area in the solar cell, is between 11 and 34%, they also explained.
According to the academics, their findings confirm that small cracks have a negligible effect on solar cell production and do not create trouble spots. They also found that a crack percentage above 46% is also insufficient for such a spot to develop. As there is a significant inactive region in the cells. Which means localized heat may be critical but not enough area to develop.
They presented the results of their work in the paper “Rapid test for the effect of cracks on output power performance solar cells and thermal function,” published in Scientific Reports. There are still some critical questions to be answered/related to this research work. An example, how cracks develop over time, they concluded. This needs to be investigated over a long-term period for solar cells operating in different environmental conditions. Rather than simply examining solar cells under artificial indoor lighting.
