Mar 07, 2019|
Today, hotspots are a major source of failure for photovoltaic modules in the field. Modules based on half-cut solar cells are an attractive pathway to reduce cell-to-module losses and are projected to have a 40% market share by 2028. However, the current standard for module testing IEC 61215-2 can leave critical hotspots undetected in such a module configuration. In this paper, the hotspot effect of half-cell modules using parallel connected cell substrings is studied in comparison with conventional full-cell modules. Significant hotspots are induced in both half- and full-cell modules, when suffering current mismatch, in this case induced by partial shading. When shaded by the same area, the hotspot temperature of the cell in a half-cell module is 19 °C lower than the full-cell module in this experimental work. Critically, multiple unshaded weak cells are found to dissipate heat when the parallel connected substring is shaded. In an experimental situation with a total shading ratio of only 4%, we measure hotspots of over 90 °C—a situation that can occur in the field due to uncontrolled plant growth and bird droppings.
|J. Qian, C. E. Clement, M. Ernst, Y. S. Khoo, A. Thomson, and A. Blakers, “Analysis of Hotspots in Half Cell Modules Undetected by Current Test Standards,” IEEE J. Photovoltaics, 1–7 (2019).||https://doi.org/10.1109/JPHOTOV.2019.2898209|