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Mirror and Absorber Qualification

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Characterization of Optical Properties of Mirrors and Absorber Coatings

The optical performance of mirror and absorber materials is essential for the efficiency of concentrating solar collectors.
The optical properties relevant for the specific concentrating solar technology are measured and evaluated with a range of reflectometer and spectrometer instruments in the laboratory.

Furthermore, procedures can be adapted to meet exceptional demands for specific CSP applications on the basis of expert knowledge and experience.

Deliverables:

• Hemispherical reflectance spectrum (solar weighted with standard solar spectrum ASTM G173)
• Solar weighted direct reflectance (within appropriate acceptance angle for specific concentrating solar technology
• Angle of specularly reflected beam diversion
• Solar weighted absorbtance
• Emittance for different temperatures of absorber materials
• Independent comparison of different materials based on standardized procedures
• Evaluation of suitability for application in concentrating solar technology
• Cost/benefit analysis of competitive products

Accelerated Aging

The risk of using innovative mirror and absorber materials in CSP applications can be reduced by testing the durability and consequently predicting the life time of the materials. For this purpose different high temperature furnaces and environmental chambers are available.

Methods:

• Analysis of degradation mechanisms of mirrors exposed outdoors
• Reproduction of natural degradation under accelerated conditions in the laboratory
• Corrosive atmospheres at elevated temperatures in the furnace
• Thermal cycling with simulation of condensation
• Exposure to elevated UV radiation (10x)
• Abrasion testing
• Analyses with standard optical characterization procedure, Light Microscopy and Scanning Electron Microscopy
• Corrosion characterization with spatial resolved reflectometer

Deliverables:

• Comparison of materials and evaluation of suitability for application in concentrating solar technology
• Identification of aging mechanisms and optimization potential
• Prediction of expected durability in terms of properties relevant for CSP applications