Classification of daylight and radiation data into three sky conditions by cloud ratio and sunshine duration

An analysis of daylight and solar radiation data in low latitude/tropics area has been done. This analysis classified three sky conditions: clear sky, intermediate sky and overcast sky. There are two methods have been used to classify these sky conditions. Firstly, cloud ratio method that is the ratio of the diffuse illuminance or irradiance to the global illuminance or irradiance. This method based on data measured at the IDMP Station at Hasanuddin University during 1995–2000. Another method is sunshine duration, which is based on the data measured at meteorological observatory in Makassar during 1995–2000. This study aims to investigate the accuracy of daylight and solar radiation data gathered during 1995–2000 by comparing data measured from two different sources above. The results of both methods are relatively similar, which indicate that daylight and solar radiation data gathered in Makassar are accurate and useful for various daylight designs and applications.