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Factors that affect the efficiency of solar energy inverters are mainly improved in two aspects: First, when converting DC current into AC sine waves, it is necessary to use a circuit using power semiconductors to switch the DC current. At this time, power semiconductors will generate heat. loss, but this loss can be minimized by improving the design of the switching circuit.
The second is to improve efficiency by virtue of inverter control experience. The output current and voltage of the solar panel will change with the sunshine and temperature, and the inverter can optimally control the current and voltage so that it can reach the maximum amount of power, that is, it can find the best power in the shortest time. The higher the power point, the higher the conversion efficiency will be. The control characteristics of the inverter will vary with the products of various manufacturers, and the conversion efficiency will also be different.
The efficiency of solar inverters refers to the growing market for solar inverters (photovoltaic inverters) due to the demand for renewable energy. These inverters require extremely high efficiency and reliability. The power circuits used in these inverters are examined and the best choices for switching and rectifying devices are recommended. The general structure of a photoelectric inverter is shown in Figure 1, and there are three different inverters to choose from. Sunlight shines on the solar modules connected in series, and each module includes a group of solar cells (Solar Cell) units connected in series. Solar modules generate direct current (DC) voltages on the order of a few hundred volts, depending on the lighting conditions of the module array, the temperature of the cells, 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 the full bridge transformer is to provide isolation. A second full-bridge converter on the output is used to convert DC from the first-stage full-bridge converter's direct current to an alternating current (AC) voltage. Its output is filtered before being connected to the AC grid network via an additional two-contact relay switch to provide safety isolation in the event of a fault and isolation from the supply grid at night. The second structure is a non-isolated scheme. Wherein, the AC alternating voltage is directly generated by the DC voltage output by the boost stage. The third structure utilizes the innovative topology of power switches and power diodes to integrate the functions of the boost and AC generation parts in a dedicated topology to make the inverter as efficient as possible despite the very low conversion efficiency of solar panels Close to 100% but very important. In Germany, 3kW series modules installed on south-facing roofs are expected to generate 2550 kWh per year. If the inverter efficiency is increased from 95% to 96%, an additional 25kWh of electricity can be generated annually. Generating this 25kWh with additional solar modules costs about the same as adding an inverter. Since increasing efficiency from 95% to 96% does not double the cost of the inverter, investing in a more efficient inverter is a logical choice. Improving solar inverter efficiency in the most cost-effective manner is a key design criterion for emerging designs. The reliability and cost of the inverter are two other design criteria. Higher efficiency improves reliability by reducing temperature fluctuations over the load cycle, so these guidelines are actually correlated. The use of modules also improves reliability.
