The performance of the collector field is affected basically by the physical properties of the absorber coating. In order to maximize solar gains and minimize heat losses, a high solar absorbtance and a low emissivity at working temperature is to be achieved.

Schematic structure and spectral reflectance of SCHOTT absorber coating

SCHOTT teamed with Fraunhofer ISE to develope a cermet absorber coating that is produced in a reactive sputtering process. The coating has a solar absorptance of 96% and an emittance at 400°C of 12%.

Tests

The first thermomechanical prototypes have been installed in June 2003 in the Eurotrough [4] at Plataforma Solar de Almeria, Spain. A field test of 100 thermomechanical prototypes has been started in Oct. 2003 at KJC, USA and is running up to now without failures. A new field test with 200 receivers will start at KJC in June 2004.

Outlook

In the follow-up project PARFOR the development activities are focused on field tests, further improvements for higher operating temperatures and cost reduction. This project is supported by the German Ministry for the Environment, project partners are the Flagsol GmbH, the German DLR and the Fraunhofer ISE.

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