Airborne Shape Measurement of Parabolic Trough Collector Fields

Kurzfassung

As the optical efficiency of the solar field has a high impact on the overall plant performance, qualification methods determining the geometrical accuracy of solar concentrator systems have gained high importance. However, it has not been possible yet to measure the geometrical accuracy of an entire solar field, resolving the relevant single characteristics like local mirror slope deviations, panel alignment and gravitational deformation. This paper describes the development and assessment of a measurement technique for the qualification of parabolic troughs based on the distant observer method called TARMES (Trough Absorber Reflection Measurement System). Instead of a stationary camera at ground level taking pictures of a turning collector, the new approach called QFly makes use of an airborne camera vehicle which allows a completely automated and fast measurement of all collectors under relevant operating conditions. The new approach was validated against a stationary TARMES and photogrammetric measurement to compare the deviations between the different methods and with the expectations of an uncertainty analysis. The absolute measurement uncertainty of QFly on a module level is around ± 0.1 milliradians.