Simple Method for Evaluating Strings of PV Cells
Easily diagnose anomalies affecting strings of PV cells
Identify which string is being affected by the anomaly while continuing to sell power back to the grid. At the junction box, use a DC clamp meter to measure the current of each string generating power that’s being sold back to the grid. The string with the anomaly will have a noticeably lower current. Compare readings for strings in the same junction box and look any discrepancy to identify which string is being affected by the anomaly.
Strings in the shade also produce clearly lower current readings, so be sure to take note of the insolation conditions at the time of measurement.