AVUSpro – Automated In-Situ Measurement of Soiling for Site Assessment and Operation of Solar Thermal Power Plants

In the project "AVUSPro" a device for the automated detection of soiling is further developed and prototypes are tested at sites with different environmental conditions. Methods for improved site characterization and improved operation of solar thermal power plants are also being developed. Here, for example, optimized cleaning and the analysis of soiling processes are important aspects.

The soiling of mirrors or reveiver/absorber elements in solar thermal power plants is highly site-specific and can even vary significantly within a power plant site. The responsible processes depend strongly on the regional and local composition of the earth's surface and soil, natural and anthropogenic emissions in the surrounding area and weather conditions. This leads to high uncertainties in yield forecasts and operating costs. Since the financing costs, yield reductions and costs for cleaning during operation, which are associated with uncertainties, represent a significant contribution to the economic viability of solar power plants, a better knowledge of the dust characteristics and soiling rates is important for the site selection and qualification of a power plant project. As installation costs continue to decrease, the issue of operating costs becomes increasingly important. Automated and cost-efficient daily determination of soiling levels during power plant operation allows for the optimization of cleaning cycles and improved short-term forecasting of yield during operation. The AVUS measuring device, further developed and improved in this project, contributes to further reducing the costs of solar power generation through risk reduction and optimization of plant operation and maintenance. Prototypes were developed and successfully tested in the AVUS project (FKZ 0325693), but further research needs were identified, addressed in the present project. Among other things, the mobile reflectometer pFlex is being developed further and a camera-based method is being tested.

The project aims at realizing cost potentials even under the influence of extreme environmental conditions, as they occur at high irradiance desert locations promising for high yield. In order to meet these requirements, tests are carried out at two locations in relevant climate zones. Methods for site characterization under different environmental influences in maritime and more continental, arid environments will be improved. Since sites can differ greatly in terms of soiling rate and other characteristics, the functional verification of device and methods at different sites is necessary for exploitation. From the field measurement data and power plant parameters, optimized cleaning techniques and cycles can be determined to increase yield while minimizing costs and water use.

In the course of the project, portable pFlex reflectometers were delivered to two operators of CSP plants. User experience is being gathered in a commercial power plant and a research facility in different climates and and their specific applications, which can be incorporated into further developments.

First results of prototypes of the AVUS measuring device for automated detection of soiling and soiling rates were collected in test operation at Fraunhofer ISE's own site in Freiburg-Hochdorf and demonstrate the functionality of the device (Figure 3). In the further course, three device prototypes were set up at different positions in the Shagaya power plant complex in Kuwait in order to also record spatial variations in soiling rates. A second site to test the prototypes in Chile is under consideration.