Abstract:
Potential Induced Degradation (PID) causes major reliability
issues, since it results in significant performance degradation and
negatively affects the durability of cells, modules and PV
systems. In this work three methods are used to induce PID on
three modules (A, B and C) by applying a voltage of 1000V to
the frame, an aluminium sheet and a plate respectively. In the
first method the voltage is applied to the aluminium frame while
the temperature is kept at 35 °C ± 1°C and humidity levels at
70% RH ± 5% RH. In the second method, an aluminum sheet
covers the glass surface without touching the frame and acts as a
positive terminal connection, temperature of 35 oC ± 1
oC and
humidity of below 40%RH. The third method, involves a smaller
aluminium plate which only covers one cell under the same
environmental conditions as for method 2. The extent of
degradation is determined by measuring the maximum power
before and after the PID stress and using Electroluminescence
(EL) Imaging taken at a current corresponding to 10% of Isc. The
power dropped by 29.6% in 288 hours, 88.7% in 48.0 hours and
6.2% in 96.0 hours in the three separate methods respectively.
This study showed that certain modules may not be easily
susceptible to PID, unless subjected to a high system voltage
over a long period of time such as modules deployed over a long
period of time in the field.
