Building integrated photovoltaic thermal (BIPVT) applications are among the cost effective solar energy applications, however, a lot of research work still needs to be done before BIPVT systems can be successfully integrated into commercial and domestic applications. This work shows the results of performance simulation study of amorphous-Si (a-Si) and crystalline-Si (C-Si) photovoltaic/thermal (solar collector in Malaysia. The results show that at solar radiation between 700-900 W/m 2 , ambient temperature between 23-34°C and fluid flow rate of 0.03 kg/s, the highest thermal and electrical efficiency of the PV/T (a-Si) was 72% and 5%, respectively, the highest thermal efficiency of (c-Si) was 51% and cell efficiency was 11.6%.