Studies of measuring and estimating of solar radiation (2nd report, Analysis of the measurements of solar radiation at Kitami Institute of Technology and calculation of solar radiation on tilted surface from that)

Abstract

For thermal engineering use of solar energy, it is important to evaluate accurately the solar radiation on a tilted surface. The results from adjusting and analyzing the measurements of solar radiation at Kitami Institute of Techonology for five years from 1978 to 1982 are as follows: An estimation equation for the direct-scattered component separation was obtained from the correlation between total radiation on a horizontal and direct radiation on a normal. The accurate value of solar radiation on a tilted surface was calculated from both the averages of total radiation graded with 2 MJ/(m2·d) each and the direct radiation. Subsequently, it was proved that the solar radiation on a tilted surface can be calculated correctly enough by means of the periodical average of th raditaiton and the direct with any distribution weight in comparison with the accurate value.