On the Application of DC Meters in Photovoltaic Power Generation Systems

In a photovoltaic power generation system (PV system), the main metering points are divided into two locations:
1.The first is at the string level. Its primary function is to be installed in the combiner box of each PV string and monitor the generated current of a single string. This is key to refined O&M, enabling the rapid location of faulty strings with inefficient power generation.

Acrel offers the AGF-AE-D photovoltaic DC string current monitoring device for PV strings. It monitors current data in real time to ensure PV system stability. Long-term monitoring can assess PV string performance and overall power generation capacity. It can also promptly detect equipment failures, improve the accuracy of back-end remote monitoring, and meet the needs of intelligent O&M.

2.The second is at the post-merger/pre-inverter level(DC combiner box). This is installed after the multiple strings are combined and before they enter the inverter. It measures the total DC input power of the entire PV array and serves as a fundamental data source for evaluating inverter conversion efficiency and overall array performance.

For monitoring DC energy consumption after PV converging, Acrel offers the DJSF1352-RN DC meter, which supports a maximum DC voltage of 1500V. Using Hall effect sensors and shunts to receive DC current signals, it provides real-time monitoring of electrical parameters and energy data, including U, I, P, Q, S, PF, F, and Energy. This allows for evaluation of overall array performance, power generation statistics, and DC-side fault diagnosis. Real-time power measurement provides the most direct data on the PV array's real-time power generation efficiency. Total DC power generation statistics provide the basis for evaluating the system's long-term performance and calculating return on investment. Comparing theoretical power generation with actual power generation allows for calculation of system efficiency. By combining historical current and power data from the gateway and EMS platform, it quickly identifies any anomalies across the entire PV array. If power is low, maintenance personnel can determine that the problem lies with the DC side (modules, strings, combiner box, etc.), rather than the inverter or AC side.