METHODS FOR THE ESTIMATION OF SOLAR ENERGY ON VERTICAL AND INCLINED SURFACES

SUMMARY This Chapter presents two methods for the assessment of monthly mean solar radiation falling on vertical and inclined surfaces anywhere in the inhabited world. Both methods involve splitting the incident flux into three components, direct, sky diffuse and ground reflected diffuse. Both methods also use mean monthly sunshine data as their starting point. The first method is relatively simple and provides daily values of the irradiation on slopes. The second method involves more complex mathematical modelling and is dependent on the availability of digital computing facilities. It rapidly produces hourly values of the mean monthly irradiance on slopes which check extremely well with field observations. This model does not assume isotropic radiation from the sky. The programs described form part of a set of climatological programs being developed in the University of Sheffield for the systematic assessment of energy gains and losses from buildings under different types of weather. The second part of this lecture is based on the work of a team consisting of Dr. G.G. Rodgers, Mr. C.G. Souster and Miss Jayne Thompson who work in a team led by the author.