Online I-V Tracer for per string monitoring and maintenance of PV panels

Large scale solar photovoltaic plants need to be monitored regularly for determining location and type of fault, cleaning schedules, operating point and performance. We propose a circuit that sits at the junction box level to provide `on demand', `online' I-V traces for series connected panels. This sparse sensing approach works on a per string basis and is therefore economical. The proposed online I-V tracer topology does not require the plant to be brought offline to obtain the I-V trace. The load's power requirement is met during the trace. The shape of the I-V trace helps determine the type of fault and localizes the fault to a specific string. The proposed solution has been tested in a practical field deployment. An analytics engine is also being developed to use the recorded I-V curve to provide optimal cleaning schedules, fault diagnosis and maintenance alerts.