Optimal orientation and tilt angle for maximizing in-plane solar irradiation for PV applications in Singapore

The performance of photovoltaic (PV) modules and systems is affected by the orientation and tilt angle, as these parameters determine the amount of solar radiation received by the surface of a PV module in a specific region. In this study, three sky models (Liu and Jordan, Klucher, and Perez et al.) are used to estimate the tilted irradiance, which would be received by a PV module at different orientations and tilt angles from the measured global horizontal irradiance (GHI) and diffuse horizontal irradiance (DHI) in Singapore (1.37°N, 103.75°E). Modeled results are compared with measured values from irradiance sensors facing 60° NE, tilted at 10°, 20°, 30°, 40°, and vertically tilted irradiance sensors facing north, south, east, and west in Singapore. Using the Perez model, it is found that a module facing east gives the maximum annual tilted irradiation for Singapore's climatic conditions. These findings are further validated by one-year comprehensive monitoring of four PV systems (tilted at 10° facing north, south, east, and west) deployed in Singapore. The PV system tilted 10° facing east demonstrated the highest specific yield, with the performance ratio close to those of other orientations.