Photovoltaic inverter conversion efficiency test solution

吹田电气SUITA

Photovoltaic inverter conversion efficiency test solution [Copy link]

Photovoltaic inverter (PV inverter or solar inverter) is an inverter that can convert the variable DC voltage generated by photovoltaic (PV) solar panels into AC power at the mains frequency, which can be fed back to the commercial power transmission system or used for off-grid power grids. Photovoltaic inverter is one of the important system balance (BOS) in photovoltaic array systems and can be used with general AC-powered equipment.

The conversion rate of a photovoltaic inverter refers to the efficiency of the inverter in converting the electricity generated by the solar panel into electricity that meets the grid standards. In a photovoltaic power generation system, the inverter converts the direct current generated by the solar panel into alternating current and transmits this alternating current to the power company's grid. The higher the conversion efficiency of the inverter, the more electricity can be used and sold at home.

Photovoltaic inverters have certain losses. In order to bring greater benefits to customers, national standards and enterprise standards have given a limit on the conversion efficiency of the whole machine, so as to regulate the inverter market and ensure the maximum interests of customers. This limit is not given blindly, but a value obtained through precise calculations and a large number of tests. The conversion efficiency of inverters with transformers shall not be less than 94%, and the conversion efficiency of inverters without transformers shall not be less than 96%. In order to win market competition, companies must improve the conversion efficiency of their products.

The Suita Electric SPAW7000 power analyzer can be equipped with SCTX/H series current sensors. When the test current is less than 50A, it can be directly connected for measurement. When the test current is greater than or equal to 50A, the Suita Electric current sensor can be connected. Without additional power supply, the open circuit voltage Vo, short circuit current Is, maximum output power Pm, voltage Vpm at maximum output power, current Ipm at maximum output power, inverter conversion efficiency and other parameters of the photovoltaic test system can be easily obtained, and the real-time data can be recorded for analysis.

Connect a high-precision power analyzer to the DC and AC sides of the inverter, and collect the DC input voltage and input current and the AC output voltage and transmission current of the inverter at full power every 50ms (20 times per second) from morning to night, and calculate the output power and output efficiency at each collection time point (every minute). In order to intuitively display the efficiency of the inverter, the conversion efficiency under different load conditions can be fitted to obtain the output efficiency distribution trend chart, and the average weighted total efficiency of the inverter can be calculated based on the conversion efficiency under different load rate conditions. When large current measurement is required, the current sensor can be used to achieve accurate measurement of multiple current levels.

Common inverter test scenarios

• Inverter conversion efficiency test

• Regular inspection and maintenance

• Accurately locate faults

• Low Pressure Ride Through

• Primary voltage and current measurement

• Secondary voltage and current measurement