Photovoltaics is an important energy technology for large scale energy generation. In the past few years cost of photovoltaic module manufacturing and installation as well as electricity generation has substantially decreased while the production volume has seen a steep increase. These changes can be attributed to improvement in solar cell efficiencies as well as better manufacturing practices. There are several photovoltaic technologies available in the market but the two primary technologies commercially manufactured for large scale installations are polycrystalline thin-film CdTe and crystalline silicon. Crystalline Si is the oldest and the most widely installed technology while thin-film CdTe is the technology that has demonstrated the largest growth and lowest LCOE (levelized cost of energy). In this study, commercial modules from both these technologies are installed side by side for an accurate comparison of their performance. The modules for comparison are installed with the same approximate nameplate capacity in three different configurations viz. Roof-top, floating on water and ground. Their performance is monitored and analyzed over a 3 month period. Thin-film CdTe demonstrated substantial advantage under all three conditions over crystalline Si in Thailand's tropical climate which is characterized by high temperatures and humidity throughout the year. Advantage demonstrated by thin-film CdTe is further supported by greater economic, environmental, reliability and life-cycle advantages that are summarized in the later part of the study.