A METHOD FOR CALCULATING THE SLOPE ERROR OF MIRRORED SURFACES CONSISTED OF FACETS CURVED IN ONE AXIS USED IN CONCENTRATED SOLAR POWER (CSP) TOWER SYSTEMS

Heliostats are considered the most important cost elements of a Concentrated Solar Power (CSP) power tower system and the use of suitable heliostats can generate reductions up to 40% in the power losses. Therefore, the design and optimization of heliostats have a great importance in solar tower power plant projects. This technical brief aims to present a method for calculating the slope error of bended-mirrored surfaces used in CSP power tower systems. For that, a heliostat composed by six mirror facets measuring 2.5 meters (width) x 0.533 meters (height) each, curved only in one axis and with a 30 meters’ focal length was considered. The found slope errors results using the numerical approach and the analytical approach were very similar, suggesting that both methods are applicable in this case.