The principle of solar photovoltaic power generation is a technology that directly converts light energy into electrical energy by utilizing the photovoltaic effect of the semiconductor interface. The key component of this technology is the solar cell. The solar cells are packaged and protected in series to form a large area solar cell module and then combined with a power controller or the like to form a photovoltaic power generation device. The whole process is called a photovoltaic power generation system. The photovoltaic power generation system consists of solar cell arrays, battery packs, charge and discharge controllers, solar photovoltaic inverters, combiner boxes and other equipment.
Why use an inverter in a solar photovoltaic power generation system?
An inverter is a device that converts direct current to alternating current. Solar cells will generate DC power in sunlight, and the DC power stored in the battery is also DC power. However, the DC power supply system has great limitations. AC loads such as fluorescent lamps, TVs, refrigerators, and electric fans in daily life cannot be powered by DC power. For photovoltaic power generation to be widely used in our daily life, inverters that can convert direct current into alternating current are 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 the solar cell and the function of system fault protection. The following is a brief introduction to the automatic operation and shutdown functions of the photovoltaic inverter and the maximum power tracking control function.
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, since the solar cell module has the characteristic that the voltage decreases as the current increases, there is an optimal operating point where the maximum power can be obtained. The intensity of solar radiation is changing, and obviously the optimal 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 control is the maximum power tracking control. The biggest feature of inverters for solar power systems is that they include the function of maximum power point tracking (MPPT).
2. Automatic operation and stop function
After sunrise in the morning, the intensity of solar radiation increases gradually, and the output of the solar cell also increases. When the output power required by the inverter is reached, the inverter starts to run automatically. After entering into operation, the inverter will monitor the output of the solar cell module all the time. As long as the output power of the solar cell module is greater than the output power required for the inverter to work, the inverter will continue to run; it will stop until sunset, even if it is cloudy and rainy. The inverter can also operate. 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 that determines the capacity of the solar cell and the capacity of the battery.
Post time: Jul-20-2022