Atmospheric Attenuation Impact on Heliostat Field Efficiency
Abstract
Concentrated Solar Power design is highly dependent on local solar radiation, atmospheric variables (i.e. water vapor content, aerosols concentration, among others) and wind velocity. In the special case of central receiver power plant, the impact of atmospheric attenuation has to be taken into account to get more accurate designs. Atmospheric attenuation impacts solar resource and heliostat field energy transmission and is neither measured nor estimated by the main solar atlas. A common heliostat field design consists of overestimating heliostat number to ensure nominal energy received at the receiver for all the range of attenuation values. Atmospheric attenuation is a physical process that does not impact all wavelengths in the same way and therefore it cannot be described as a single atmospheric attenuation without losing its physical meaning. This work is focused on obtaining atmospheric attenuation values from ground data using a numerical model and describes step by step how it should be applied to estimate heliostat field attenuation.