Effect of Solar Brightness Profiles on the Performance of Parabolic Concentrating Collectors

Solar brightness profiles were used to model the optical performance of a parabolic linear solar concentrator. A sensitivity analysis of the sun size on collector performance was completed using analytical methods. Ray traces were created for solar brightness profiles having circumsolar ratios from 0–40%, slope errors of the optical surface from 2–5 mrads, and angles of incidence varying from 0–60 degrees. Using typical meteorological data for two locations, the optical performance was calculated and averaged over a year. Intercept factors of these simulations were compared to simpler analytical models that cast the sun shape as a Gaussian function. Results showed that collector performance is relatively insensitive to solar profile, and that using a representative Gaussian solar profile will tend to underestimate collector performance compared to using exact weighted solar profiles by about 1%. This difference is within the uncertainty propagation of the intercept factor calculated with analytical methods.