Photovoltaic Modules Self-Testing by Junction Box-Embedded Wireless Monitoring Solution

Online monitoring of PV systems is essential to detect failures on the PV system, improve performance ratio and minimize degradation, extending module lifespan and increasing profitability by optimizing maintenance activities, reducing in-field inspections. PV system or string level monitoring approaches often fail to detect faults in individual modules, while module-level methods are more expensive. This work introduces a low-cost IoT device embedded in the junction box of the PV modules, which estimates the I-V characteristic near the operating point without disconnecting the PV module from the rest of the system, while also monitoring modules substrings and bypass diodes. The embedded circuit produces and measures small variations around the operating point to obtain, for the entire PV module and at substring level, the I-V characteristic around the operating point. From this information, for each PV module two numbers are obtained: degradation and misfit. In addition, the proposed solution would be able to estimate several PV module parameters as series and shunt resistances or saturation currents.