Solar Resource
The earth receives in the region of 174PW (petawatts) (Rhodes, 2010) of incoming solar radiation, also referred to as insolation, at the outer atmosphere. The sun’s rays that reach the outer atmosphere are subjected to absorption, reflection, and transmission processes through the atmosphere before reaching the earth’s surface as shown below in Figure 1. According to Neuwirth (1980) the earth’s surface topography has to be taken into account as the solar radiation shows different appearances at different altitudes.
Based on reviews of Burnett (2012) and Garg & Garg (1993), solar radiation and sunshine duration are two main parameters that can be measured at weather stations to estimate the solar radiation resource. Solar radiation can be directly measured using a Pyranometer. Alternatively sunshine duration can be measured using a Campbell Stokes Recorder but is then required to be converted into solar radiation using the Suehrcke method (Suehrcke, 2000).
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Graham Cairns
University of Edinburgh, 2013
University of Edinburgh, 2013