A SIMPLE METHOD FOR CORRECTING SOLAR RADIATION MEASUREMENTS MADE USING NON CALIBRATED EPPLEY-TYPE AND ROBITZSCH-TYPE PYRANOMETERS

In regard to high normal inherent errors in solar radiation data obtained by the Robitzsch-type pyranometer, a simple method is proposed to reduce these errors considerably by improving the accuracy of estimations of average daily irradiation on a horizontal surface recorded by this kind of actinographs. This method is also proposed for correcting the experimental results gathered using noncalibrated Eppley-type pyranometer. The procedure starts by determining two daily distributions of clear sky solar radiation at the studied location. One of these distributions is constructed using measurements by an accurate instrument used as reference for this purpose, while the other one is based on the actinograph or/and noncalibrated Eppley-type pyranometer in use. The correction factor can be deduced then by relating these two distributions with taking into consideration climatic conditions and life-time behaviour of the instruments. The obtained correction factor is found to be highly dependent on the ambient te...