September has arrived, the weather is still hot. According to the Central Weather Bureau, the national rainfall in early September into the "rest period", most of the northern regions of the day and night temperature difference significantly increased, the southern high temperature weather in the short term still continue.
As this summer the country continues to high temperature, many photovoltaic power plant owners believe that this weather is conducive to power station generation, can sit back and wait for the income to be credited. In fact, the summer high temperature is not equal to the power station high power, high temperature, strong humidity will instead give the power station to increase the burden, bringing many adverse effects. The impact of high temperature weather on the components are mainly the following.
Lead to PV module output power drop
PV modules generally have 3 temperature coefficients: open circuit voltage, peak power, short circuit current. When the temperature rises, the output power of PV modules will drop. The peak temperature coefficient of PV module is about -0.38 ~ 0.44% / ℃, that is, the temperature increases, the PV module power generation decreases, theoretically, each degree of temperature increase, the power generation of photovoltaic power plant will be reduced by about 0.44%.
Impact on open-circuit voltage leads to insufficient system charging
Silicon solar cells work at higher temperatures, the open-circuit voltage drops significantly with the increase in temperature, which also leads to a serious shift in the charging operating point, making the system vulnerable to damage due to undercharging. Solar cell short-circuit current rises with temperature.
In actual research cases, the output power of crystalline silicon solar cells at a temperature of about 20 degrees is about 20% higher than at 70 degrees. In other words, if the location where the PV plant is installed has average lighting conditions, but the average annual temperature is relatively low, then it is actually beneficial to the PV solar plant, and its power output is much higher than in areas with too much light and too high temperatures.
Affect the service life of the core components of the inverter
In photovoltaic systems, photovoltaic modules are afraid of heat, the same inverter is also afraid of heat. The inverter is composed of many electronic components, and the main parts will generate heat when working. Manufacturers will use heat sinks and fans in the design and development process in order to reduce the heat inside the machine. If the temperature of the inverter is too high, the performance of the components will be reduced, which will affect the life of the inverter.
Therefore, the installation of inverters in the construction of photovoltaic power plants usually take into account the issue of ventilation and cooling, while the laying of wires and cables, the design and installation of the array should take into account whether the temperature can be reasonably applied to avoid the negative impact of temperature on photovoltaic solar power plants.
Formation of hot spot effect affects module life
Excessive local temperature will produce hot spots, which will affect the life of PV modules. The hot spot effect refers to the fact that under certain conditions, a solar cell module that is shaded in a tandem branch will be used as a load to consume the energy generated by other solar cell modules that have light, and the shaded solar cell module will heat up at this time. The hot spot effect will destroy the solar cell to a certain extent, part of the energy produced by the solar cell with light may be consumed by the shaded cell, and the hot spot effect of the PV plant will directly lead to a 30% shortening of the service life of the PV module, which may cause the module to fail in the long run.
PID effect causes module failure
PID effect, also known as potential induced decay, is the phenomenon of ion migration between the encapsulation material of the cell module and its upper and lower surface materials, and the high voltage between the cell and its grounded metal frame, which causes the module performance to decay. Improper cooling of PV power plant in hot weather will easily produce PID effect and cause module failure.
China's vast territory, a variety of climatic environments are mostly present. As the temperature rises, the photoelectric conversion efficiency will also decline. For example, in most areas of China due to the climate environment, there will be a common temperature loss of 2%, 3%, in the tropics under high temperature conditions caused by the loss will reach about three times above, which directly leads to the power station power generation reduced.
Photovoltaic power plants are susceptible to the effects of hot weather, which can be improved to some extent by a reasonable system installation design. Ensure the ventilation and heat dissipation of the modules and inverters, distribution boxes, reasonable design layout according to local conditions, timely removal of accumulated ash on the PV panels, ensure that the modules are surrounded by open and free of debris, and pay attention to cable maintenance in order to achieve the most ideal power generation revenue.
