Comparative study of single-junction and triple-junction a-Si:H PV modules in hot and humid climate

With efficiency of PV devices approaching theoretical numbers and cost of PV coming down, the most essential factor that would determine their large scale deployment is the reliability and durability of the PV modules and the balance of system components. The degradation mechanism and reliability issues in PV cells must be determined by the tests carried out on field-deployed modules. With this goal outdoor testing of PV modules was undertaken. The outdoor performance variation of commercially available single junction and triple junction a-Si:H PV module has been studied in the hot and humid climate of Florida. After the initial Staebler-Wronski degradation, the a-Si:H PV modules typically degrade during the winter time when the temperatures are low and recuperate due to the annealing that takes place during the summer time. Due to this seasonal variation, the monthly data was considered in the multiples of 12. Performance variation calculated from the monthly PTC power showed +1.89±0.58% and +2.49±0.6% for positive and negative array of single junction a-Si:H PV modules and +0.42±0.87% and + 0.56±0.89% for the positive and negative array of triple junction a-Si:H PV modules respectively. The annual energy yield was found to be 1300 kWh/kWp/year and 1425 kWh/kWp/year for the single junction and triple junction a-Si:H PV arrays respectively.