After 4 years of operation at Thailand Science Park, degradation analysis of 73 photovoltaic (PV) modules of four different PV technologies; multi c-Si, hetero-junction Si, micromorph and CIGS, has been carried out. The degradation rate (DR) of individual modules and array performance are presented. It was found that some micromorph (thin film Si 1) modules seriously degraded and were in failure mode, resulting in a severe degradation of the thin Si 1 array's performance. The average DR of other PV modules was found to range between 0.3 and 1.9%/year. The standard deviation (SD) of data from modules in the same array indicates the level of mismatch, which plays a role in evaluating array's performance. The levelized cost of electricity (LCOE) in this study was found to range between 4.1 and 14 baht/kWh, depending on PV technology and its DR. The results suggest that, without any reduction of costs, the LCOE of solar PV electricity in Thailand would possibly be comparable with the retail price when the present PV technology has DR of about 0.2%/year or lower. The database we obtained is informative and useful for a further study on PV reliability and cost of solar PV electricity in the tropics. (C) 2016 Elsevier Ltd. All rights reserved.