Moo 2, Banpraod Sub-District, Parprayom District, Phatthalung (Thailand) 2Regional Office of Alternative Energy and Development and Efficiency (Area 4), Ratchaburi (Thailand) 3Electrical Engineering Division, Abstract--This paper aims to investigate the performance produced at large central power plants and transmitted of a 20 kWp grid connected PV system which consists of long distances to the end users across a wide network of monocrystalline-Si, CdTe thin film and a-Si thin film solar transmission and distribution lines. On the other hand, in arrays and grid connected type inverter operated under the a distributed system, power is produced at or close to the environment of Thailand. Results showed that solar radiation intensity was the main factor affecting the yield of point of use. Distributed systems avoid the cost and each solar array. The final yield of monocrystalline Si, CdTe losses of transmission and distribution. PV systems for thin film and a-Si thin film solar arrays were in the range of building have no connection to the utility grid and often 2.44-3.57 h/d, 2.38-3.56 h/d and 2.40-3.58 where the rely on a set of batteries to store power for use at night performance ratio of monocrystalline-Si, CdTe thin film and during periods of insufficient solar radiation and a-Si thin film solar array were in the range of 55-59%, intensity. In a grid connected or utility interfacing system, 54-58% and 55-59% respectively. The average efficiency of the building receives electricity from both the PV array the solar array was 9.78% for monocrystalline-Si, 5.33% for and the utility grid. Some PV systems are capable of both CdTe thin film and 4.62% for a-Si thin film. Finally, the stand alone and the utility interfacing modes of operation.average system efficiency was 6.72% for monocrystalline-Si, PV electricity is produced by an array of individual PV 3.50% for CdTe thin film and 3.17% for a-Si thin film. modules electrically connected in series and parallel to deliver the desired voltage and current. Each PV module, P nex .rato Sol Ciells in turn, is constructed of individual solar cells also connected in series and parallel. However, grid connected