Improvement of approaches to the composition, diagnosis and operation of solar modules under ununiform lighting conditions

Solar modules, which are used in photovoltaic power plants, are the primary sources of energy, and it is on their efficient operation that the generation of electricity by the station depends. During operation, solar modules can be exposed to various natural and man-made impacts. As a result, its effectiveness may decrease, or its may fail. The world practice of monitoring the state of an energy source at a solar power plant, based on measurements of the electrical parameters of PV-strings consisting of series-connected solar modules, does not fully reflect the changes in their possible states. There is practically no information about the performance of individual modules. In this regard, the development of mathematical models for the connections of photovoltaic converters (PVCs), methods for detailed monitoring and diagnostics of the technical condition of solar modules in order to detect violations in a timely manner and subsequently increase the efficiency of its operation in non-uniform lighting conditions, are urgent tasks that require new solutions.

An explicit analytical equation for the full current-voltage characteristic of a photovoltaic converter was obtained using the Lambert W-function for the forward and reverse branches. An electronic measuring unit was developed that allows automatically recording the current-voltage characteristic of converters, including the negative branch. When solar cells are connected in series under conditions of non-uniform illumination of its surface, some of the least illuminated solar cells stop working as energy sources and become “parasitic” loads. The bulk of the PV cells continue to generate power and pass current through the less illuminated PV cells, causing high energy losses in the form of heat dissipation, which can lead to the formation of hot spots and thermal damage to the PV cells. A significant influence of the reverse branch of the current-voltage characteristic of a photovoltaic converter on the generated power is shown. A method for composing solar modules from photovoltaic converters under their operating conditions with non-uniform illumination is proposed, the technical result is to increase the efficiency and reliability of the power plant by reducing the frequency of replacing failing solar modules due to the formation of local overheating points. A diagnostic unit for the solar module has also been developed, which allows you to automatically monitor the health status of each module and notify in a timely manner about the need for maintenance, repair or replacement of solar modules on the territory of a solar photovoltaic power plant.

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