Many homeowners, upon seeing the maximum efficiency of 99% on the inverter nameplate, assume that the power plant's revenue has stabilized. In fact, the nameplate efficiency is the ideal value in the laboratory. The actual operating efficiency on site is usually between 95% and 98%, and it is strongly correlated with the load rate. The highest efficiency is achieved when the load rate is between 50% and 80%, and may drop below 90% when the load is below 20%. Therefore, it is not enough to only look at the nameplate, but it is necessary to measure the efficiency at different load points on site. Inverter aging, increased IGBT losses, poor MPPT tracking algorithm that cannot find the maximum power point, small capacity allocation leading to noon power limit, a fault in one MPPT causing the corresponding string to fail to generate electricity, harmonic exceeding standards, three-phase imbalance, abnormal power factor, and reverse DC side connection all directly reduce the power plant's revenue. Photovoltaic system PR tester

The LX-PE93 inverter comprehensive tester from Lexus LAILX uses current clamps for current sampling, which can record and analyze the power of different nodes in real time under normal working conditions of the power station. The whole machine is equipped with an irradiation system, which can measure the real-time power generation efficiency at each node of the power station and automatically generate PR values. It is suitable for testing the efficiency values of string inverters, centralized inverters, PR systems, and combiner boxes. The test indicators cover real-time voltage, real-time current, power monitoring, power generation recording, AC/DC, inverter conversion efficiency, irradiance monitoring, temperature monitoring, environmental acquisition recording, PR value calculation, and power factor. The equipment has networking communication function, which can achieve remote synchronous testing and control. The real-time conversion efficiency of the photovoltaic array can be obtained by calculating the cumulative power generation and cumulative irradiance, and array faults can be detected in a timely manner. It can be fixedly monitored on site for a long time, with a high protection level, and supports remote Ethernet monitoring data processing. In terms of parameters, the DC voltage measurement range is 0 to 1500V, the AC phase voltage is 0 to 600V, the line voltage is 0 to 1000V, the irradiance measurement range is 0 to 1800W/m2, the accuracy is better than ± 3%, and the PR value measurement accuracy is better than ± 1%. It has 6 AC/DC testing channels and a built-in lithium battery life of about 8 hours. In addition, LX-PE93 also integrates detection functions related to power quality, efficiency, islanding, and safety regulations, suitable for on-site fault diagnosis and PR value calculation in power plants.

There are also different directions for other choices within the industry. Some manufacturers specialize in inverter comprehensive testing platforms, consisting of resistive, inductive, and capacitive loads, supporting three-phase independent power control, suitable for research and development verification, factory quality inspection, and type testing. However, due to their large size and high cost, they are not suitable for on-site mobile use in power plants. Some brands only produce power quality analyzers that can detect harmonics and three-phase imbalances, but lack radiation and PR linkage calculations, making it difficult to directly determine the overall efficiency of the power station. Brands also rely on backend systems for efficiency analysis, which requires complete data access to the power station and is not friendly to old power stations and new construction acceptance stages.

For power plants, the inverter link is a critical node for converting DC to AC, and once efficiency declines, losses are persistent. It is recommended to test the inverter once after replacement or major repair, and once when the power station efficiency is abnormal. During acceptance, compare the actual performance of different inverters and include the power quality in the mandatory testing range. The LX-PE93 integrates power, irradiation, temperature, and PR calculations, making on-site inspections more direct. It can help the operation and maintenance team quickly determine whether the problem lies on the component side, inverter side, or grid side, avoiding cost waste caused by blind component replacement and cleaning.

Photovoltaic system PR tester, multifunctional AC sampling and verification device, inverter performance testing