Further development of the air-based method for the characterization of heliostat fields and preparation for industrial application
In solar thermal tower systems, heliostats are a key component. Previously used methods for calibrating the heliostat orientations are very time-consuming and therefore costly, as they calibrate the heliostats from the ground sequentially and individually over their focal spot on a white target area on the solar tower (target), interrupting power plant operation. This is especially so during the commissioning phase of a new power plant. Innovative techniques using aerial drones allow the mirrors to be calibrated in much less time. The air-based calibration can be carried out much faster than the conventional method and is therefore more cost-effective. In the previous joint project HelioPoint, DLR researchers and partners developed and tested such a method at the Spanish test center Plataforma Solar de Almería (CIEMAT) and at DLR's solar thermal test power plant in Jülich. However, further development work is required before it can be used in large commercial power plants.
The follow-up project HelioPoint-II aims to extend the existing methods so that they also meet the requirements for use in commercial solar tower power plants with a large number of heliostats to be measured. This requires the upscaling of the method to commercial power plant size, which is accompanied by greater accuracy and higher speed, as required for use in industrial environments. The manual calibration of each heliostat is not possible in large-scale, commercial solar tower power plants.
In the HelioPoint-II project, the Institute of Solar Research and the company CSP Services will investigate individual elements of the new process in more detail, improve them further and adapt them for industrial use for different heliostat technologies so that it can be applied to different heliostat types. DLR's work will focus on:
The new generation of unmanned aerial vehicles (UAVs) and advanced camera technology open up new possibilities for solving technical challenges in solar power plants. High-precision positioning methods such as real-time kinematic (RTK) and post-processed kinematic (PPK) are now available as hardware for commercial drones, providing a better position indication in real time or by post-correction than before.
To validate the method, the heliostat array of an associated industrial partner will be calibrated with the required accuracy and speed and manual comparison measurements will be performed. The aim is to perform the tests in a commercial tower power plant in Spain and to test the method in an industrial environment.
Basically, the innovative, air-based calibration procedure offers considerable advantages over conventional methods that work with the position of the sun. The HelioPoint measurement technique works at any time of year and independent of the position of the sun. In addition, the new method eliminates the need for sequential and time-consuming alignment of the mirrors to a target area on the solar tower (target). Calibration can be performed before the power plant is commissioned, independent of the construction progress of other power plant components. The significantly reduced measurement time of the method at commercially reasonable cost not only lowers the cost of calibration, but can also shortens the construction time of a power plant. This is a tremendous advantage over established methods. The airborne method allows a new power plant to ramp up more quickly, reaching its rated output a year earlier. Model calculations by the consortium show that this reduces a power plant's cost of electricity (LCOE) by 1.2 percent and reduces technical risks, such as those posed by poorly calibrated heliostats that can damage tower or power plant areas.
Supported by the Federal Ministry for Economic Affairs and Climate Action