Investigation of the surge immunity of monocrystalline silicon photovoltaic modules using dark current-voltage and 1/f noise power spectrum density characteristics

Surge immunity of commercialized p-type monocrystalline Si photovoltaic (PV) modules was investigated using dark current-voltage (I-V) and 1/f noise power spectrum density (PSD) characteristics. The IEC 61000-4-5 (IEC: International Electrotechnical Commission) standard method was employed as the surge immunity tests for PV modules assembled with and without the bypass diode. The PV module without bypass diode was capable of withstanding surge test at ±6.0 kV with the consistent of insignificant degradation in dark I-V curve and noise PSD level. On the other hand, for the PV module with bypass diode, the leakage current was unchangeable as increasing surge magnitude up to ±2 kV. However, after surge test at ±3.0 kV, the PV module with bypass diode showed a rapid increase in reverse leakage current and 1/f noise PSD, followed by a complete failure after ±3.5 kV. This implied that bypass diode could be a major cause of the PV module failure at high surge voltage stress though they could guard the PV module from the damage of low surge voltage strikes. Namely, the bypass diode for the application of PV modules should guarantee the class 4 (4 kV) of IEC61000-4-5 standard in order to ensure the long-term reliability of PV systems.