Comparative Study of Four Shadow Band Diffuse Irradiance Correction Algorithms for Almerı́a, Spain

Abstract

Diffuse irradiance is a fundamental component in solar resource considerations. Diffuse irradiance can be accurately determined by calculation from global and beam normal (direct) measurements. However, beam solar measurements can be expensive and therefore shadow bands are often used along with pyranometers to mask the solar disk. The errors that result from the use shadow bands are well known and have been studied by numerous authors. The thrust of this article is to examine four recognized correction techniques for correcting shadow band based diffuse irradiance and statistically evaluate their individual performances using data collected in Almerı́a, Spain. Almerı́a is located in southern Spain and has a healthy solar irradiation budget.