EFFECT OF COOLING ON PARASITIC RESISTANCES OF SOLAR PHOTOVOLTAIC MODULES IN AN UNCONTROLLED ENVIRONMENT
Publication Date : 17/07/2019
The current study investigated the effect of cooling on parasitic resistances of solar PV modules in an uncontrolled environment. An experimental setup comprising of two solar PV modules were subjected to the same external conditions and the data were collected between the hours of 09:00 to 16:00 with one of the solar modules been subjected to cooling process using a DC submersible pump. The DC submersible pump was consistently controlled (power ON/OFF) by module's surface temperature. The results have shown that solar PV module series resistance RS tends to decrease as module's temperature decreases through the process of cooling from 4.49Ω to 2.53Ω, whereas its shunt resistance RSH increases with decrease in module's temperature from 92.83Ω to 335.89Ω. The relationship between modules' output power, Pmax and series resistances, RS were established to be exponential functions. Modules' output power, Pmax and equivalent resistances, Req were observed to be exponentially related. Under initial power condition of RS=0, the solar module maximum power with cooling and without cooling unit were found to be 132.49W and 92.45W respectively. Under ideal solar module condition of Rs→0 and RSH→∞, there was 8.6% improvement in maximum power resulting from effect of cooling. Short circuit current and output power were also observed to be linearly related with negative gradients. Hence, minimising solar PV module temperature through the process of cooling caused equivalent, and series resistances to decreases but shunt resistance increases; the cumulative effect was exponential increase in solar module maximum power.
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