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Hot Cells in High-Power Photovoltaic Modules with Solar Cells from Larger Silicon Wafer Formats
R. Witteck, M. Siebert, I. Kunze, M. Köntges
Reliability, Shading, PV Module
Photovoltaic Modules and BoS Components
Subtopic: PV Module Design, Manufacture, Performance and Reliability
Event: 38th European Photovoltaic Solar Energy Conference and Exhibition
Session: 4AV.1.25
757 - 760
ISBN: 3-936338-78-7
Paper DOI: 10.4229/EUPVSEC20212021-4AV.1.25
0,00 EUR
Document(s): paper


We demonstrate that partial shading of a single c-Si solar cell in a state-of-the-art high-power photovoltaic (PV) module with three bypass diodes can result in hot cells with critical module peak temperatures of 196 °C. The PV module under test features 144 bi-facial PERC+ half-cells of M6 silicon wafer format with a cell area of (166 x 83) mm2. The module’s measured maximum power output is 437 WP. We test three cells of the PV module in an extended IEC 61215-2 MQT09 hot-spot endurance test for 5 h in a steady-state sun simulator. All shaded cells reach steady-state temperatures above 175 °C. For the hottest cell we measure peak temperatures of 196 °C at the module surface. After the test the PV modules shows a discoloration of the white backsheet at the position of the shaded solar cells. This is likely to result in a module power loss or module failure due to encapsulation discolorations, desoldering of the cell interconnection, backsheet cracking of even glass breakage. Our results are essential for improving the long-term stability of new high-power modules with M10- or M12-sized cells and power outputs over 500 WP against partial shading. New high-power modules require hot cell mitigation techniques that go beyond three bypass diodes per module or heat-resistant module materials.