A novel climate-specific field accelerated testing of PV modules

Failure modes and degradation rates of PV modules in a specific climate are primarily dictated by the module design and field-specific climate stressors such as temperature, UV and humidity. To identify the long-term design issues and predict lifetime of PV modules, the plant owners, investors and researchers typically utilize long-term indoor accelerated tests such as extended/modified IEC 61215 tests. Though the indoor accelerated tests can appropriately be designed for the environmental stressors of a specific climate, several challenges are encountered and they include: capital and operating costs of multiple walk-in environmental and weathering chambers for commercial size modules; only statistically insignificant number of commercial modules can be tested at a time due to size limitation of the chambers, and; multiple climate-specific temperatures and multiple humidity profiles used in the long-term accelerated tests prevent performing conventional IEC 61215 test profiles inside the same chamber. All the above-mentioned challenges can be adequately addressed using a novel climate-specific field accelerated testing setup presented in this work. This test program has been designed specifically for the hot-dry desert climate where the environmental stressors are temperature and UV with little or no influence from humidity. This program can easily be modified for the other climatic conditions, e.g. test setup for a hot-humid condition can include temperature, UV and humidity. In the current outdoor accelerated test program for hot-dry desert climate, the temperature acceleration is achieved by inserting heavy thermal insulators on the backside of the modules and the UV acceleration at higher operating temperatures are achieved by using a V-trough solar concentrator on the thermally insulated PV modules installed on a 2-axis tracker. An acceleration factor of about 12-15 is expected depending on the activation energy of the climate-specific degradation mechanism, e.g. encapsulant browning and solder bond degradation.