The efficiency of solar inverters refers to the growing market of solar inverters (photoelectric inverters) due to the demand for renewable energy. And these inverters need extremely high efficiency and reliability. The power circuits used in these inverters are reviewed and the best choices for switches and rectifiers are recommended. The general structure of a photovoltaic inverter is shown in Figure 1. There are three different inverters to choose from. Sunlight shines on solar modules connected in series, and each module contains a series of solar cell units connected in series. The direct current (DC) voltage generated by solar modules is on the order of several hundred volts, and the specific values depend on the lighting conditions of the module array, the temperature of the battery, and the number of modules connected in series.
The primary function of this type of inverter is to convert the input DC voltage to a stable value. This function is implemented by a boost converter and requires a boost switch and a boost diode. In the first configuration, the boost stage is followed by an isolated full-bridge converter. The role of a full-bridge transformer is to provide isolation. A second full-bridge converter on the output is used to convert the direct-current DC of the first-stage full-bridge converter into an alternating current (AC) voltage. Its output is filtered before being connected to the AC grid network via an additional two-contact relay switch, with the aim of providing safe isolation in the event of a fault and isolation from the power grid at night. The second structure is a non-isolated scheme. The AC alternating voltage is directly generated by the DC voltage output by the boost stage. The third structure uses the innovative topology of power switches and power diodes to integrate the functions of the boost and AC AC generation parts in a dedicated topology. Although the conversion efficiency of the solar panel is very low, the inverter efficiency is as much as possible Close to 100% is very important. In Germany, a 3kW series module installed on a south-facing roof is expected to generate 2550 kWh per year. If the inverter efficiency is increased from 95% to 96%, an additional 25kWh can be generated each year. The cost of generating this 25kWh with an additional solar module is comparable to adding an inverter. Since increasing the efficiency from 95% to 96% will not double the cost of the inverter, investing in a more efficient inverter is an inevitable choice. For emerging designs, the most cost-effective way to improve inverter efficiency is a key design criterion. As for the reliability and cost of the inverter, there are two other design criteria. Higher efficiencies can reduce temperature fluctuations over the load cycle, thereby increasing reliability, so these guidelines are actually related. The use of modules also improves reliability.
