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Efficiency of solar inverter battery




Efficiency of Solar inverters refers to the growing market for solar inverters (photoelectric inverters) due to the demand for renewable energy. These inverters require extremely high efficiency and reliability. The power circuits used in these inverters are investigated and the best choice of switching and rectifying devices is recommended. The general structure of the photoelectric inverter is shown in Figure 1, and there are three different inverters to choose from. Sunlight strikes Solar modules connected in series, each of which contains a series of solar cells. The direct current (DC) voltage generated by solar modules is on the order of several hundred volts, depending on the lighting conditions of the module array, the temperature of the battery, and the number of modules in series.




The primary function of this inverter is to convert the input DC voltage into a stable value. This function is achieved through 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. The second full-bridge converter on the output is used to convert the DC to AC (AC) voltage from the full-bridge converter at the first stage. Its output is filtered before being connected to the AC grid network via additional two-contact relay switches to provide security isolation in the event of a failure and isolation from the supply grid at night. The second structure is a non-isolation scheme. The AC 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 generation parts in a dedicated topology. Although the conversion efficiency of solar panels is very low, it is important to keep the efficiency of the inverter as close to 100% as possible. 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%, it can generate 25kWh more electricity per year. Using additional solar modules to generate that 25kWh costs about the same as adding an inverter. Since increasing efficiency from 95% to 96% does not double the cost of inverters, investing in more efficient inverters is an inevitable choice. The most cost-effective improvement of inverter efficiency is a key design criterion for emerging designs. As for inverter reliability and cost are the other two design criteria. Higher efficiency can improve reliability by reducing temperature fluctuations over the load cycle, so these criteria are actually related. The use of modules also improves reliability.




The function of solar inverter battery




Battery inverter not only has the direct alternating current transformation function, but also has the maximum limit to carry forward the function of solar cell and system fault maintenance function. It boils down to active operation and shutdown function, maximum power tracking control function, prevention of independent operation function (for grid-connected system), active voltage adjustment function (for grid-connected system), DC detection function (for grid-connected system), DC ground detection function (for grid-connected system). The active operation and shutdown function and the maximum power tracking and control function are briefly introduced here.




1. Active operation and shutdown function: after sunrise in the morning, the solar radiation intensity is gradually strengthened, and the output of the solar cell is also increased. When the output power required by the inverter task is reached, the inverter is actively started to operate. After entering the operation, the inverter will watch the output of the solar cell components every moment, as long as the output power of the solar cell components is greater than the output power required by the inverter task, the inverter will continue to run; Until sunset shutdown, even rainy inverter can operate. When the output of the solar cell module becomes small and the output of the inverter is close to 0, the inverter will form standby mode.




2, the maximum power tracking control function: the output of the solar cell module is changed with the solar radiation intensity and the temperature of the solar cell module itself (chip temperature). In addition, because the voltage of solar cell module decreases with the increase of current, there is an optimal task point to obtain the maximum power. The solar radiation is changing, and obviously the optimal mission point is also changing. Related to these transitions, the task point of the solar cell module is always at the maximum power point, and the system is always getting the maximum power output from the solar cell module. This restraint is the maximum power tracking restraint. The most characteristic of the inverter used in solar power system is to include the maximum power point tracking (MPPT) this function.

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tom lee

tom lee

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