We have conducted potential induced degradation (PID) tests on CIGS photovoltaic (PV) modules with/without LED white light irradiation. Suppression of PID degradation was observed by light irradiation.
Based on our results that conventional damp-heat (DDH) test on a commercial CCIGS (a.k.a. CCIS, CIGSS) module causes an irreversible "Test-specific" degradation (TSD) that is not observed in modules deployed in fields, we propose a new option for DDH testing of CIGS modules. We have tested full-size CIGS modules with/without forward bias, light irradiation and humidity during heat tests. The results clearly show that adding forward bias, or white light irradiation during DH tests suppresses this irreversible degradation. Based on these results, we have proposed to add forward bias and/or light irradiation during DH tests of CIGS modules, to make the test condition closer to real fields and suppress degradations not observed in the field.
Photovoltaic (PV) modules, operate at high voltages and elevated temperatures, and are known to degrade because of leakage current to ground. Related degradation processes may include: electric/ionic corrosion, electrochemical deposition, electromigration, and/or charge build-up in thin layers. The use of polymeric materials with a high resistivity is known to reduce the rate of potential induced degradation processes. Because of this, PV materials suppliers are placing increased importance on the encapsulant bulk resistivity, but there is no universally accepted method for making this measurement. The development of a resistivity test standard is described in this paper. We have performed a number of exploratory and round-robin tests to establish a representative and reproducible method for determining the bulk resistivity of polymeric materials, including encapsulation, backsheet, edge seals, and adhesives. The duration of measurement has been shown to greatly affect the results, e.g., an increase as great as 100X was seen for different measurement times. The standard has been developed using measurements alternating between an "on" and "off" voltage state with a weighted averaging function and cycle times of an hour.
Current injected damp heat (CDH) test have been reported to accelerate certain type of long-term degradation observed in at least one prototype flexible thin film silicon photovoltaic (PV) modules deployed in field . This report have raised a question that whether conventional DH tests should be combined with current injection or light illumination to better reproduce long-time degradations of flexible thin film modules. To answer this question, we have been testing multiple flexible products available in the market, as part of the activities of Japanese Task Group 8 of the International PV Quality Assurance Task Force (PVQAT) . Here, we present some results of our damp (or dry) heat testing with light illumination on a flexible CIGS module product with relatively poor moisture barriers.
Current injection during damp heat (DH) test have been reported to accelerate certain type of long-term degradation observed in of photovoltaic (PV) modules deployed in field. In this paper, we present the current status of our damp heat testing with current injection or light irradiation on flexible PV modules, with some preliminary results.