What Are the Functions and Characteristics of Photovoltaic Inverters

The inverter not only has the function of DC to AC conversion, but also has the function of maximizing the performance of solar cells and the function of system fault protection. In summary, there are automatic operation and shutdown functions, maximum power tracking control functions, anti-solitary operation functions (for grid-connected systems), automatic voltage adjustment functions (for grid-connected systems), DC detection functions (for grid-connected systems), and DC grounding detection function (for grid-connected systems).

The following briefly introduces the automatic operation and shutdown functions and the maximum power tracking control 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 starting to run, 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; it will stop until sunset, even on cloudy and rainy days 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.

The output of the solar cell module varies with the intensity of solar radiation and the temperature of the solar cell module itself. 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, and 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 maximum power tracking control. The biggest feature of the inverter used in the solar power generation system is that it includes the function of maximum power point tracking.

1. Higher efficiency. Due to the high price of solar cells at present, in order to maximize the use of solar cells and improve system efficiency, it is necessary to try to improve the efficiency of the inverter.

2. High reliability. At present, the photovoltaic power station system is mainly used in remote areas, and many power stations are unattended and maintained. This requires the inverter to have a reasonable circuit structure, strict component selection, and requires the inverter to have various protection functions, such as input DC Polarity reversal protection, AC output short-circuit protection, over-temperature and overload protection, etc.

3. The input voltage has a wide range of adaptation. Since the terminal voltage of the solar cell changes with the load and the intensity of sunlight, especially when the battery ages, the terminal voltage varies greatly. For example, for a 12V battery, the terminal voltage may vary between 10V-16V, which requires The inverter guarantees normal operation within a large DC input voltage range.