Soiling Effect in a Central Receiver Solar Plant under Real Outdoor Conditions

Reflectance loss is assessed on heliostats of the very-high concentration solar tower facility located in Mostoles, near Madrid, Spain. This region is characterized by an annual direct normal irradiance availability around 1,900 kWh/m(2), which makes it economic viable for concentrating solar power (CSP) plants. Moreover, its location nearby a highly populated area and one of the busiest highways in Spain, introduces additional features relevant in soiling analyses. The reflectance loss was measured with a Condor reflectometer on thirteen single-facet heliostats, in which nine of them are in different locations of the solar field and tilted 10 degrees south, while four of them are side by side with different tilt angles, also turned in the same direction. The aim is to evaluate the soiling effect in an urban environment, to assess the soiling ratio and rates through the solar field, and to identify possible stow positions to reduce the soiling effect.