QFly
The optical and thermal efficiency of parabolic trough solar fields depends on the function and condition of its components such as the concentrator, absorber and tracking system. The Qualification Department of the Institute of Solar Research is developing measurement methods to assess the condition of the components in existing power plants.
In order to optimize the field and localize problematic areas, it is essential to create a complete overview of the optical properties of the solar field. QFly utilizes airborne imaging techniques and an associated software package to provide information on the geometric, optical and thermal properties of the solar field .
QFly consists of three complementary measurement methods:
- 'QFly HighResolution', a method based on the ► TARMES principle, can be used to determine the mirror shape and receiver position with high spatial resolution.
- 'Survey' obtains similar results from a great height (120 meters) with low resolution and also information about the relative alignment of individual modules.
- 'Thermo' is used to screen for heat loss and is particularly useful for detecting receivers with defective vacuum insulation.
The collectors identified using QFly-Survey can be subjected to a targeted and efficient high-resolution analysis using QFly-HighResolution. This high-precision measurement provides the mirror shape (RMS < 0.1 mrad) of the concentrator and, relative to this, the position of the receiver tubes and their positional deviation from the focal line (RMS < 1 mm).
The QFly-Survey application is used for the general characterization of large solar fields. A series of images is taken from an altitude of around 120 meters, making it possible to examine each individual collector for possible deficiencies in mirror shape, module alignment, torsion or tracking deviations. Within a few hours, it is possible to measure and characterize an entire commercial power plant. Individual collectors with particularly conspicuous characteristics are identified in this context and examined in more detail at a later stage.
QFly-Thermo is used for automated and GPS-referenced thermal screening of the receivers. Defective or damaged receivers and pipe sections with excessive heat losses are localized in the solar field.
QFly has been licensed as a software product and is widely used in the industry. For example, the companies CSP Services and Volateq offer characterizations and services for commercial CSP power plants and PV parks based on the QFly code.
The functionality of the original QFly code has now been refactored within DLR as part of the Optical Measurement Toolbox (OMTool). In addition to the characterization of parabolic trough solar fields, further evaluation routines can be developed on the basis of OMTool, for example in order to investigate and characterize heliostat fields in solar tower power plants. Among other things, current projects investigate how misaligned heliostats can be identified as efficiently as possible with the help of airborne measurements and artificial intelligence. In addition, the functionality of OMTool can be used to characterize the geometries of PV parks and thus serve as a basis for further analyses (e.g. by the meteorology group to characterize the soiling of PV modules).