Ukraine, Oles Honchar Dnipro National University.

The overheating caused by electrical loads is one of the essential factors impairing the reliability of photovoltaic components of solar cells. The most common technical solution to this problem is to use such additional elements as bypass diodes. However, the practice of installing such diodes in parallel with a chain of solar cells has shown that this approach does not eliminate hot spots completely, and thus characteristics of the solar cells deteriorate at a faster pace. One of the possible solutions to this problem is to use critical thermistors based on metal-semiconductor phase transition materials, such as vanadium dioxide. Structurally, such thermal protection is implemented by adding a separate photovoltaic element with a thermistor protection element that is in thermal contact with it. This study investigated the effectiveness of such a solution to prevent local overheating in photovoltaic components of solar cells. Glass-ceramic materials based on vanadium dioxide and vanadium-phosphate glass of the V₂O₅—P₂O₅ system were used as thermistor elements, which abruptly change the electrical resistance by 1.5—2.0 orders of magnitude in the temperature range around 700С. The research results showed that the considered protective elements can function as reusable (self-healing) fuses against electrothermal overloads in solar batteries. Considering the relative simplicity and low cost of the manufacturing technology of glass-ceramic materials with a metal-semiconductor phase transition, the described approach to preventing overheating of photovoltaic cells of solar cells in situations with higher reliability requirements appears to be promising.

Keywords: critical thermistor, vanadium dioxide, photovoltaic element, local overheating.

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