As well known, potential induced degradation (PID) strongly decreases the performance
of photovoltaic (PV) strings made of several crystalline silicon modules in hot and wet climates. In
this paper, PID tests have been performed on commercial copper indium gallium selenide (CIGS)
modules to investigate if this degradation may be remarkable also for CIGS technology. The tests
have been conducted inside an environmental chamber where the temperature has been set to 85
°C and the relative humidity to 85%. A negative potential of 1000 V has been applied to the PV
modules in different configurations. The results demonstrate that there is a degradation affecting
the maximum power point and the fill factor of the current‐voltage (I‐V) curves. In fact, the
measurement of the I‐V curves at standard test condition show that all the parameters of the PV
modules are influenced. This reveals that CIGS modules suffer PID under high negative voltage:
this degradation occurs by different mechanisms, such as shunting, observed only in
electroluminescence images of modules tested with negative bias. After the stress test, PID is
partially recovered by applying a positive voltage of 1000 V and measuring the performance
recovery of the degraded modules. The leakage currents flowing during the PID test in the chamber
are measured with both positive and negative voltages; this analysis indicates a correlation between
leakage current and power losses in case of negative potential.
