The influence of solar cell junction temperature and sunlight intensity on the output characteristics of solar cell is given by
And the equivalent circuit shows that the sunshine intensity and the cell junction temperature are the most important parameters that affect the power output of the solar cell array. The change of the solar cell junction temperature depends on the sunshine intensity, as shown in Figures 1 and 2.
As shown in Figure 1(a) and Figure 2(a), the output short-circuit current Isc and the maximum power point current Im of the solar photovoltaic array increase with the increase of sunlight intensity, but the change of sunlight has an effect on the output open circuit voltage Uoc of the array. The impact is not so great, and the maximum power point voltage Um does not change much. As shown in Figure 1(b) and Figure 2(b), temperature has little effect on the output current of the solar photovoltaic array. The short-circuit current Isc increases slightly with the increase of temperature, but it has a greater impact on the output open circuit voltage Uoc, and the temperature rises. The open circuit voltage Uoc of the solar cell will decrease, and it will decrease almost linearly with the increase of temperature. The overall effect will cause the output power of the solar cell to decrease. Note that this refers to the change in the junction temperature of the solar cell, not the change in the ambient temperature. PV manufacturers generally give the short-circuit current Iscn, open-circuit voltage Uocn, maximum power point voltage Ump, and maximum power point current of solar panels under standard test conditions (light is 1000w/m², temperature is 25°C, and frequency spectrum is 1.5) for modules produced by photovoltaic manufacturers. Imp and other parameters.
Several important technical parameters of solar cells;
①Short-circuit current (Isc); the maximum output current under a given sunshine intensity and temperature. The value of Isc is related to the area of the solar cell. The larger the area, the greater the value of Isc. For the same solar cell, the Isc value is proportional to the irradiance of the incident light. When the junction temperature of the cell increases, the Isc value rises slightly.
②Open circuit voltage (Uoc): The maximum output voltage at a given sunshine intensity and temperature. (The size of Uoc is proportional to the logarithm of the incident spectral irradiance, and has nothing to do with the area of the battery. When the junction temperature rises, The Uoc value will decrease.
③Maximum power point current (Im): The current corresponding to the maximum power point under a given sunshine intensity and temperature.
④ Maximum power point voltage (Um): The voltage corresponding to the maximum power point under a given sunshine intensity and temperature.
⑤Maximum power point power (Pm): The maximum power that the solar cell array may output under a given sunshine intensity and temperature, Pm=Um·Im. When the junction temperature rises, the total output power of the solar cell will decrease, while the sunshine Strengthening will increase the power of the battery, but it will also increase the junction temperature of the battery.