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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 fault protection. In summary, there are automatic operation and shutdown functions, maximum power tracking control MPPT function, anti-solitary operation function (for grid-connected systems), automatic voltage adjustment function (for grid-connected systems), DC detection function (for grid-connected systems), and DC grounding Detection function (for grid-connected system).

1. Automatic operation & shutdown function of photovoltaic inverter

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.

2. MPPT function of photovoltaic inverter

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 solar inverters used in solar power generation systems is the function of maximum power point tracking. There are three different algorithms for maximum power point tracking: perturb-and-observe, incremental conductance and constant voltage. The first two are often called "hill climbing methods". The method is to follow the curve of voltage to power, if it falls to the left of the maximum power point, increase the voltage, and if it falls to the right of the maximum power point, decrease the voltage.