Application of non-contact electrostatic voltmeter to identify underperforming modules in grid-connected photovoltaic systems

This paper presents a technique that uses maximum power point voltage (Vmpp) to quantitatively identify the underperformance photovoltaic (PV) modules in grid-connected PV systems using a non-contact Electrostatic Voltmeter (ESV). Unlike the other existing techniques, this technique doesn't require the module's disconnection from the grid or other modules in a string. First, in this work, the ESV was tested for the application of thin film modules (off-grid and on-grid), and a comparison of the ESV sensed voltages with the voltmeter voltage values indicated a difference of less than 2%. Second, the least power-producing module was identified by the IV curves analysis and the Vmpp technique, and the results were compared. The comparison of both characterization tools quantitatively pointed out to the same module as the lowest performance module. It is a contactless, time and cost-saving method and is useful for quantitatively determining defective and poor-performing PV modules in large power plants where continuity of the energy production is preferred during the testing.