Automatic fault diagnosis in PV systems with distributed MPPT

• An automatic failure diagnosis procedure for PV systems with DMPPT is presented.
• The different failures diagnosed and their effects on the PV systems are described.
• No use of irradiance and temperature sensors decreasing the cost of the system.
• Voltage and current analysis to diagnose different failures.
• Hot-spots, localized dirt, shading, module degradation and cable losses diagnosis.

This work presents a novel procedure for fault diagnosis in PV systems with distributed maximum power point tracking at module level—power optimizers (DC/DC) or micro-inverters (DC/AC). Apart from the power benefits obtained when an irregular irradiance distribution is present, this type of systems permit the monitoring of the PV plant parameters at the module level: voltage and current at the working power point. With these parameters, a prototype diagnosis tool has been developed in Matlab and it has been experimentally verified in a real rooftop PV generator by applying different failures. The tool can diagnose the following failures: fixed object shading (with distance estimation), localized dirt, generalized dirt, possible hot-spots, module degradation and excessive losses in DC cables. In addition, it alerts the user of the power losses produced by each failure and classifies the failures by their severity. This system does not require the use of irradiance or temperature sensors, except for the generalized dirt failure, reducing the cost of installation, especially important in small PV systems.