Case Studies and Site Verifications of I-V Curve Implemented by Smart Inverters | 智慧變流器的IV曲線判讀實例與實證


Mr. Ya-Tsung Feng / 馮雅聰

Product Manager 

Ablerex Electronics Co., Ltd 




  • Product Manager, Ablerex Electronics Co., Ltd 




The accumulative installed capacity of PV power in Taiwan has reached 3.5GW. PV power developers and investors have been experiencing O&M (operation and maintenance) issues on sites, which significantly impact ROI (return on investment). Therefore, the best O&M practices during 20-year whole life of PV power plants would be the top priority to investors and staff.

PV professionals are aware that the International Electrical Code IEC62446-1 (Photovoltaic systems – Requirements for testing, documentation and maintenance –Part 1: Grid connected systems – Documentation, commissioning tests and Inspection) can be conducted as the initial acceptance of a power plant, periodic maintenance testing, and verification standards before transferring PV assets. And they learn that the standard has pointed out a number of key indicators and operational and test details. But these key items have not been implemented, due to huge numbers of labor services, redundant works on site and additional financial requirements.

In order to maintain the expected ROI, EPC/SI firms are eager to significantly lower labor and engineering costs with safe operation and optimal power generation. ABLEREX, who is the leading PV inverter manufacturer with professional service team in Taiwan, has launched string I-V curve performance measurement technology granted an invention patent on inverter products and cloud PV management system.


O&M staff performs the string I-V curve performance measurement without additional equipment burden and it is not necessary to dispatch engineers to the site. As Annex D of IEC 62446-1, all curve variation types could be shown on the PV cloud management platform, at least including 1) steps or notches in curve, 2) low current, 3) low voltage, 4) rounder knee, 5) shallower slope in vertical leg, 6) steeper slope in horizontal leg, when deviations are discovered. The shape of an I-V curve can provide valuable information on the string/array under tested MPPT. Variable defects may be identified, including damaged modules, short circuited bypass diodes, local shading, module mismatch, the presence of shunt resistance in modules / arrays, and excessive series resistance.



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