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Photovoltaic panels are exposed to various external factors that can cause damage, with the formation of cracks in the photovoltaic cells being one of the most recurrent issues affecting their production capacity. Electroluminescence (EL) tests are employed to detect these cracks. In this study, a methodology developed according to the IEC TS 60904-13 standard is presented, allowing for the calculation of the percentage of type C cracks in a PV panel and subsequently estimating the associated power loss. To validate the methodology, it was applied to a polycrystalline silicon module subjected to incremental damage through multiple impacts on its rear surface. After each impact, electroluminescence images and I-V curves were obtained and used to verify power loss estimates. More accurate estimates were achieved by assessing cracks at the PV cell level rather than by substring or considering the entire module. In this context, cell-level analysis becomes indispensable, as the most damaged cell significantly influences the performance of the photovoltaic model. Subsequently, the developed methodology was applied to evaluate the conditions of four photovoltaic panels that had been in operation, exemplifying its application in maintenance tasks. The results assisted in decision making regarding whether to replace or continue using the panels.

The shadow effect caused by nearby objects or the lack of cleaning significantly affects the performance of photovoltaics (PV) installations. This article analyses the bypass diode electrical behaviour and the thermal response of a PV crystalline module under shading or soiling conditions. PV cells of different substrings were covered progressively to simulate the effect of shading or soiling while a programmable electronic DC load was connected to a PV module to set an operating voltage. Three different tests were made to different PV crystalline technology. The paper characterizes in real conditions the I−V curve, bypass diode current, and front and back side PV cell temperature with contact sensor and infrared (IR) thermography, respectively. The results showed that the operation voltage established in the PV module defines the electrical bypass diode current and thermal response under normal operating conditions, shading or soiling. To show the bypass diode behaviour in such conditions, I−V curves were obtained, pointing out the value of the current that flows through bypass diodes in the whole voltage range.