The Role of Inverters In Solar Photovoltaic Power Generation Systems
Feb 17, 2023
Inverter is a device that converts direct current into alternating current. Solar cells generate direct current in sunlight, and the storage battery is also direct current. However, the direct current power supply system has great limitations. AC loads such as fluorescent lamps, TVs, refrigerators, and electric fans in daily life cannot be powered by direct current power. In order for photovoltaic power generation to be widely used in our daily life, an inverter that can convert direct current into alternating current is indispensable.
As an important part of photovoltaic power generation, the photovoltaic inverter is mainly used to convert the direct current generated by photovoltaic modules into alternating current. The inverter not only has the function of DC-AC conversion, but also has the function of maximizing the performance of solar cells and the function of system failure protection. The following is a brief introduction to the automatic operation and shutdown functions and maximum power tracking control functions of photovoltaic inverters.
1. Maximum power tracking control function
The output of the solar cell module varies with the intensity of solar radiation and the temperature of the solar cell module itself (chip temperature). In addition, because the solar cell module has the characteristic that the voltage decreases with the increase of the current, so there is an optimal operating point that can obtain the maximum power. The intensity of solar radiation is changing, obviously the best working point is also changing. Relative to these changes, the operating point of the solar cell module is always at the maximum power point, and the system always obtains the maximum power output from the solar cell module. This kind of control is the maximum power tracking control. The biggest feature of the inverter used in the solar power generation system is the function of maximum power point tracking (MPPT).
2. Automatic operation and shutdown function
After sunrise in the morning, the intensity of solar radiation increases gradually, and the output of solar cells increases accordingly. When the output power required by the inverter is reached, the inverter starts to run automatically. After entering the operation, the inverter will monitor the output of the solar cell components all the time, as long as the output power of the solar cell components is greater than the output power required by the inverter, the inverter will continue to run; until the sunset stops, even if it is rainy The inverter also works. When the output of the solar cell module becomes smaller and the output of the inverter is close to 0, the inverter will form a standby state.
In addition to the two functions described above, the photovoltaic inverter also has the function of preventing independent operation (for grid-connected system), automatic voltage adjustment function (for grid-connected system), DC detection function (for grid-connected system), and DC grounding detection function (for grid-connected systems) and other functions. In the solar power generation system, the efficiency of the inverter is an important factor in determining the capacity of the solar cell and the storage battery.
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