Photovoltaic (PV) system comprising PV modules and related control system is the sole means through which the solar energy is converted directly into electricity. The PV module is generally rated according to its maximum DC power output (Wp) which is obtained under Standard Test Condition. However, this condition is seldom encountered, especially in the high temperature and variable irradiance climate like Malaysia. On the other hand, in the actual operating conditions, the energy generated from PV module is sturdily influenced by surrounding climate; hence, a performance evaluation model for PV system is necessary. This research proposes a mathematical algorithm to calculate the hourly, monthly and annually expected PV system energy output, considering the actual PV module temperature (Tm) increase effect. The new algorithm was developed due to the limitation in the existing methodologies particularly the one used in Malaysia by Malaysian Green Technology Corporation (MGTC). The developed Tm prediction model is based on the pre-processed hourly data measured for 9 months at the 92 kWp Building Integrated Photovoltaic (BIPV) GreenTech Malaysia, Bangi, Selangor which includes Tm, ambient temperature (Ta), solar irradiance (G), wind speed (Ws) and Relative Humidity (RH). The developed algorithm was compared to the model used by MGTC and validated with actual measurements. In addition, 5 years of hourly data for Ta, G, and Ws measured at 6 different locations in Malaysia obtained from Malaysia Meteorological Department were used for development of a solar radiation and energy output estimation models. The proposed energy model gives good result since it is closer to measured data compared to the PVWatts simulation tool. Results on the techno-economic analysis are also presented. The proposed energy output estimation model is expected to be useful for the PV system installer in the pre-installation phase in terms of feasibility and performance analysis of the PV system
