A Novel Portable Device to Measure Transmittance and Reflectance of Parabolic Trough Receiver Tubes in the Field

The performance of parabolic trough (PT) receiver tubes (RTs) has a direct impact on concentrated solar power (CSP) plant production. As a result, one major need of operation and maintenance (O&M) in operating plants is to monitor the state of the receiver tube as a key element in the solar field. In order to fulfill this necessity, Abengoa Solar has developed the first existing portable device for measuring the transmittance and reflectance of parabolic trough receiver tubes directly in the field. This paper offers a description of the technical features of the instrument and reviews the issues related to its usability as a workable portable device in operating solar fields. To evaluate its performance, laboratory studies have been carried out using two patterns to determine the accuracy and standard deviation of the measurements, obtaining excellent results. This information is complemented with data collected by O&M using this instrument in solar power plants. Studies have been carried out to determine the effect of both rainfall and artificial cleaning on the increase of transmittance. These values are then compared to those obtained from hand-cleaning, and show important differences. The results are discussed in this paper.