This summer, numerous parts of China experienced the hottest temperatures ever recorded in the history of complete meteorological observation. With the sun so large and the temperature very elevated, many people think that the efficiency of photovoltaic power plants will also increase. Is that true?
"In continuous hot weather, the power output of PV modules shows a negative temperature coefficient relationship. The higher the temperature, the lower the power output, so the generation will decrease accordingly." Fan Guoyuan, secretary-general of the Jiangsu Photovoltaic Industry Association, who has long studied the development of the photovoltaic industry, mentioned that the ideal working temperature of photovoltaic power modules is about 25℃, and every 1℃ increase in temperature will reduce the output power by about 0.35%, and the power generation of photovoltaic power stations will also be reduced by about 0.35%.
Fan Guoyuan introduced that the photovoltaic power generation system is composed of photovoltaic modules, controllers, batteries, inverters and other parts. The power generation principle is to use the photovoltaic effect generated by the light irradiation of semiconductors to directly convert light energy into electricity. In general, better light conditions do produce additional electricity in the summer. But extreme heat is another matter. Extreme high temperatures in summer not only affects the power and performance of photovoltaic modules, but also may cause damage to photovoltaic components such as photovoltaic inverters.
Experts introduce that photovoltaic modules, tuv solar cable typically have three temperature coefficients, open circuit voltage, peak power and short circuit current. Among them, the open-circuit voltage will decrease significantly with the increase of temperature, resulting in the offset of the operating point, affecting the performance of the module, the output power of the photovoltaic module will decrease. The components in the photovoltaic inverter also have rated operating temperatures. If the ambient temperature is very high, the temperature of the inverter at full power will rise quickly. When the operating temperature of the photovoltaic inverter exceeds the threshold, the output power will be limited, and even the overtemperature standby protection will be triggered, which will accelerate the aging of the inverter components, affect the life of the photovoltaic power station, and increase the operation security risks of the power station. Therefore, extreme summer temperatures cannot be equated with peak photovoltaic power generation.
In the actual operation of photovoltaic power station, how much influence does elevated temperature have on photovoltaic power generation? The reporter also verified the long-term professional engaged in the operation of photovoltaic power stations.
"Taking a completely on-grid 2.55 megawatt PV plant in Changzhou as an example, monitoring data showed that the total generating capacity of the plant in July this year was 289,000 KWH and 280,000 KWH in August, compared with 269,000 and 257,000 KWH in the same month last year."
The reporter found that in July this year, the average sunny day temperature in Changzhou ranged from 29℃ to 37.3℃, and the average daily power generation of the power station was 13,000 KWH. The average temperature on sunny days in August ranges from 30.5 C to 39.25 C, and the plant generates an average of 12,800 KWH of electricity per day. Last July, the average sunny day temperature ranged from 25 ° C to 33 ° C, and the plant generated 14,400 KWH of electricity every day. Last August, the average sunny day temperature ranged from 24.5 ° C to 35 ° C, and the plant generated 13,600 KWH of electricity per day on average.
"Through data comparison, it can be seen that although the temperature this year is higher than the same period last year, the average daily power generation in July this year is 8.4% lower than the same period last year, and the average daily power generation in August is 6.08% lower than the same period last year. It can be seen that the elevated temperature has a great adverse impact on the photovoltaic power generation per unit time under the same conditions."