Performance of inclined heliostat solar field with solar geometrical factors

The solar tower power plant (STPP) is one of the most renowned technologies for large-scale renewable electricity production. The solar field of STPP is made up of several hundreds of mirrors, known as heliostats. The orientation of each heliostat is time dependent and follows the actual sunpath in two-dimensions and focuses the solar flux to the receiver. There is a strong relationship between the solar geometrical factors and the amount of solar flux reflected from the mirror to the receiver. The present paper aims to evaluate critically the time-variant performance of inclined heliostat solar field and examines the performance in reference to the distinctive positions of sun-earth geometry (solar solstices and equinoxes) and solar geometrical factors. The analysis encompasses the criticality of the investigations in terms of cosine efficiency, shadow and blocking efficiency, field optical efficiency, intercept efficiency, flux distribution on the receiver, etc. It is observed that the average field efficiency is the highest at equinox with 76% followed by winter solstice (73%) and summer solstice (68%). It is observed that in the morning and evening time when the zenith angle is high during winter solstice and equinox, the field optical efficiency of the inclined surface solar field increases 12-13% and 1%, respectively, in comparison to the flat surface solar field. The average total shadow-blocking-intercept efficiency of inclined surface solar field is found to be 11.28%, 4.66%, and 6.23% higher than flat surface solar field during the winter solstice, summer solstice, and equinox, respectively. In the present analysis, atmospheric attenuation efficiency is found to be 0.2% higher for the inclined surface.