Quoted from:Page JK. The estimation of monthly mean values of daily total short wave radiation on vertical and inclined surfaces from sunshine records for latitudes 401N–401S. In: Proceedings of UN conference on new sources of energy; 1961 .p .378–90.

https://digitallibrary.un.org/record/3827996

INTRODUCTION

Page has provided the coefficients of the modified Angstrom type model, which is claimed to be applicable anywhere in the world:

\( H/H_0 =0.23+0.48 S/S_0 \)

A technique for caloulating monthly mean values et total dail,y radiation on inclined surface. from sunahine data has been proposed.

The first part deals nth the oalculation of mean value of total radiation on horizontal planes, using the oonventional type of regression equation.

The second part deals with the separation of the mean horizontal ditffuse radiation from the total radiation, using a regression equation of the form

The third part of this paper deal with the conversion of direct radiation on the horizontal plane to direct radiation on inclined Planes.

The fourth part ot this paper deal with the estimation ot diffuse radiation on inolined surfaces using the isotropic approximation.

The need for further field observations is stressed also the fact that the method of analysis is restricted to monthly mean values of possible sunshine and so is not applicable to daily values of sunshine. The accuracy of prediction appears to be of the order of 5% for monthly meana. It is shown that collector orientation for maximum efficiency is influenced very much by the diffuse radiation climate in any locality and it is suggested that attention must be given to the problem of properly utilising this diffuse energy in flat plate collectors, particularly in the humid tropics where half the available energy may be diffuse.