The PV applications in Thailand are now installed more than 1.2 GWp cumulatively. It is due to the National Renewable Energy Program and its targets. In the latest Alternative Energy Development Plan (AEDP), the PV electricity production target has increased from 2 GWp to 3 GWp. With this rapid growth, customers and manufacturers seek for module standard testing. So far over one thousands of PV modules per annum have been tested since 2012. The normal tests include type approval test according to TIS standard, acceptance test and testing for local standard development. For type test, the most module failure was found during damp heat test. For annual evaluation test, the power degradation and delamination of power was found between 0 to 6 percent from its nameplate after deployment of 0 to 5 years in the field. For thin-film module, the degradation and delamination was found in range of 0 to 13 percent (about 5 percent on average) from its nameplate for the modules in operation with less than 5 years. However, for the PV modules at the reference site on campus operated for 12 years, the power degradation was ranging from 10 to 15 percent. Therefore, a long term performance assessment needs to be considered to ensure the system reliability.
PV rooftop system can generally be installed to produce electricity for the domestic house, office, small enterprise as well as factory. Such a system has direct useful for reducing peak load, meanwhile it also provides shaded area on the roof and hence the heat gain into the building is reduced. This study aims to investigate the shading effect on reduction of heat transfer into the building. The 49 kWp of PV rooftop system has been installed on the deck of the office building located in the middle of Thailand where the latitude of 14 ° above the equator. The estimation of heat gain into the building due to the solar irradiation throughout a day for one year has been carried out, before and after the installation of the PV rooftop system. Then the Newton’s law of cooling is applied to calculate the heat gain. The calculation and the measurement of the heat reduction are compared. Finally, the indirect benefit of the PV rooftop system installed is evaluated in terms of power value.