A typical solar power system consists of four main parts: solar panels, a charge controller, a solar inverter, and a battery. Solar panels provide direct current (DC) power, converting solar energy into electrical energy. The charge controller is responsible for controlling the energy conversion. The solar inverter converts the DC power from the solar panels into alternating current (AC) power for storage in the battery. The battery stores the AC power for human use. The solar inverter plays a crucial role in the entire solar power system, acting as a bridge between the solar panels and the battery.
Features of solar inverters
The main characteristics of solar inverters are centralized inversion and string inversion. Solar power systems are generally very large-scale. Using a single inverter for each solar panel would be wasteful and impractical. Therefore, in actual production, solar inverters centrally invert the direct current (DC) generated by all the solar panels, converting it into alternating current (AC). Thus, the size of a solar inverter must generally match the size of the solar panels. A single solar inverter obviously cannot meet this requirement, leading to another characteristic of solar inverters: they are often used in strings.
Functions of solar inverters
Inverters not only have DC-AC conversion capabilities, but also the ability to maximize the performance of solar cells and system fault protection functions. These can be summarized as follows: automatic operation and shutdown functions, maximum power point tracking (MPPT) control functions, anti-single-operation functions (for grid-connected systems), automatic voltage regulation functions (for grid-connected systems), DC detection functions (for grid-connected systems), and DC grounding detection functions (for grid-connected systems). Here, we will briefly introduce the automatic operation and shutdown functions and the maximum power point tracking (MPPT) control functions.
1. Automatic Operation and Shutdown Functions: After sunrise, the intensity of solar radiation gradually increases, and the output of the solar cells also increases accordingly. When the output power required for the inverter's operation is reached, the inverter automatically starts operating. Once in operation, the inverter continuously monitors the output of the solar cell modules. As long as the output power of the solar cell modules exceeds the output power required for the inverter's operation, the inverter continues to operate until sunset, even on cloudy or rainy days. When the output of the solar cell modules decreases and the inverter output approaches zero, the inverter enters standby mode.
2. Maximum Power Point Tracking (MPPT) Function: The output of a solar panel changes with the intensity of solar radiation and the temperature of the solar panel itself (chip temperature). Furthermore, because the voltage of a solar panel decreases as current increases, there exists an optimal operating point where maximum power can be obtained. Since solar radiation intensity varies, the optimal operating point also changes. To keep the operating point of the solar panel at its maximum power point, ensuring the system consistently obtains maximum power output from the solar panel, is called maximum power point tracking (MPPT). A key feature of inverters used in solar power systems is the inclusion of MPPT functionality.
