Five-year performance and reliability analysis of monocrystalline photovoltaic modules with different backsheet materials

Elevated operating temperatures decrease the energy yield and reliability of photovoltaic (PV) systems. In order to minimize these thermal losses and stresses, different types of packaging materials for PV modules need to be examined with respect to their electrical and thermal performance but also their reliability and durability. This study analyses the performance and reliability of identical monocrystalline Silicon PV modules with different backsheet materials including aesthetically enhanced all-black PV modules employing black backsheets. The modules were installed to form grid-connected systems with an approximate nominal capacity of 1.2 kWp, and were exposed under the warm climatic conditions of Cyprus. The results of the five-year evaluation period showed that despite the use of black backsheets, temperature improvements were achieved verifying that backsheets influence the cell temperature and enhance performance by operating at lower temperatures. More specifically, the comparative analysis of the thermal behavior, based on acquired cell temperature measurements, verified that backsheets can be designed to influence the cell temperature and enhance performance by operating at lower temperatures in some cases up to 10 °C. The systems with the backsheets that retained lower operating temperatures produced higher annual energy yield, under the warm conditions exposed due to reduced thermal losses. In particular, the annual energy yield results showed that the systems equipped with the white control and black color thermal management backsheet produced consistently the highest annual energy yield over the evaluation period. Finally, the results of the indoor and outdoor degradation rate analysis showed that, over the five-year period, there was no significant difference in the estimated degradation rate amongst the installed systems, since the results are within the uncertainty range.