The efficiency of the inverter refers to the ratio of the output power and the input power under the specified working conditions, expressed as a percentage. In general, the nominal efficiency of the photovoltaic inverter refers to the pure resistance load, the efficiency of 80% of the load. Due to the high overall cost of photovoltaic system, it is necessary to maximize the efficiency of photovoltaic inverter, reduce the system cost, and improve the cost performance of photovoltaic system. At present, the nominal efficiency of mainstream inverters is between 80% and 95%, and the efficiency of low-power inverters is not less than 85%. In the actual design process of photovoltaic system, not only should choose the high efficiency inverter, but also through the reasonable configuration of the system, as far as possible to make the photovoltaic system load work near the best efficiency point.