ABSTRACT
In order to estimate the amount of solar energy striking a surface one must determine the location of the sun relative to the surface at any given time on any given day. There are several quantities that are required in order to estimate the intensity of solar radiation on the Earth’s surface. This chapter lists these items such as the apparent solar irradiation at air mass zero, atmospheric extinction coefficient, indirect coefficient and declination. Solar calculations are often linked with monthly average solar and weather data. Along with the direct normal solar radiation, there is an indirect component of solar energy which will strike a surface. This indirect component is diffused or scattered solar energy which comes from the sky. If the direct solar radiation is a little high, the indirect solar radiation will be a little less than an average day.
