Soiling and Abrasion in Photovoltaics
Soiling and Abrasion in Photovoltaics

Cleaning Resistance of Solar Glass Coatings

Glass Abrasion Tester
© Fraunhofer CSP
The abrasion tester developed at Fraunhofer CSP can be used to test the resistance of surfaces to cleaning processes.

Due to the accumulation of dust and other contaminants on the surfaces of photovoltaic modules or solar thermal mirrors (CSP), significant yield losses can occur. To avoid these, regular cleaning of the glass surfaces is usually carried out.

This regular cleaning results in high mechanical loads on the glass surfaces, which nowadays are usually provided with anti-reflective coatings. Damage to these coatings due to cleaning leads to significant, irreversible losses in yield, which means high financial risks for plant operators, investors and plant manufacturers.

Fraunhofer CSP operates standardized test facilities with which glass surfaces of solar energy systems (up to PV module formats) can be tested with regard to their resistance to real cleaning loads in Europe and desert regions. In addition, the damage potential of user-specific cleaning parameters and materials can be evaluated at Fraunhofer CSP.

Test Washing System for Rotating Brush Cleaning

Large-area test washing system
© Fraunhofer CSP
The large-area test washing system offers the possibility of full-surface abrasion tests with wet-rotating brush cleaning and defined dust-water suspensions.
Brushes test washing machine
The abrasion resistance of coatings to standardized and application-specific cleaning loads with different brush types can be tested.

With the test washing system, we offer our customers the possibility of full-surface abrasion tests by means of wet-rotating brush cleaning and precisely definable dust-water suspensions.

In working mode 1 (normative quantitative), the abrasion resistance of coatings to standardized cleaning loads (defined test dust, defined brush and cleaning parameters) can be determined.

Working mode 2 (normative qualitative) offers the possibility to evaluate the damage potential of user-specific brushes and cleaning parameters against standard cleaning conditions from operating mode 1: For example, test dusts, brush types and brush speeds can be compared.

During test cleaning, the reflectance increase (due to ARC degradation) is recorded as a function of the number of brush cycles. We then use optical reflectance spectroscopy to determine in-situ the abrasion-induced reduced antireflectance.

You would like to conduct an abrasion test with rotating brushes performed on defined contaminated samples? Please contact us!

Mobile Abrasion Tester for Linear Brush Cleaning

Abrasion teste
Abrasion tester developed at Fraunhofer CSP for testing the resistance of surfaces to cleaning processes.

To determine the cleaning resistance of surface coatings on smaller areas, we offer customers the use of a mobile abrasion tester with linear brush cleaning.

We use defined test dust (Arizona test dust A2 fine according to ISO 12103), of which a small amount is initially distributed dry and evenly on the glass surface. After a typical set of test cycles (100, 200, 300, 400 and 500) we evaluate the transmittance and reflectance according to IEC 62805-2 before applying more dust.

You would like to conduct abrasion tests with linear brushes on defined contaminated samples? Please contact us, wet cleaning is also possible on request.