Laboratory Measurements for Determining the Temperature Coefficients of Photovoltaic Modules Using New Installation

The main parameter to ensure the optimal operation of the photovoltaic system is to determine its position of this system in accordance with the available solar radiation in the location. Nevertheless, in order to predict the performance of a photovoltaic system, it is important to know the ambient temperature, since the temperature of solar cells affects the output parameters of the system, which is expressed in temperature coefficients. Thus, it is possible to optimize the operation of the photovoltaic system by varying the temperature of the elements using design solutions such as a heat sink or photothermal conversion system.

The article demonstrates the operation of own development installation for measuring the parameters of solar cells. The results of measurements to determine the temperature coefficients of thin-film elements using this installation are presented. For comparison, we have measured the output parameters of a monocrystalline modules and thin-film photovoltaic modules (PM) based on amorphous silicon, CdTe, and CIGS at various temperatures from 20 to 80 °C.

The changes in the output power of PMs at various operating temperatures are calculated in comparison with the values under standard testing conditions (STC). The parameters measured at various temperatures are normalized to STC. The temperature dependences of the normalized values of the maximum output power, fill factor, short circuit current, and open circuit voltage are presented. Decrease in the open circuit voltage is observed with an increase in temperature in all modules. The sharpest decrease in the fill factor with increasing temperature is observed in the monocrystalline module, in combination with a decrease in open-circuit voltage, it showed the biggest decrease in output power, 15.9%, 20.4% and 25.1% at temperatures of 60 °C, 70 °C and 80 °C, respectively. It is proved that all PMs based on thin-film technologies have smaller values of the temperature coefficient of the output power in comparison with a monocrystalline modules, the smallest of which is for CdTe.

The further tasks are set to develop hardware and software for improvement of the installation to provide the dynamic changes in the intensity of illumination, temperature and wind speed defined by a program.

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