article posted 6 April 2016
Stefan Karlsson is since 2012 a researcher and project manager at Glafo – the Glass Research Institute. He holds a BSc in chemical engineering (2006) from Växjö University, Sweden and a PhD in Glass Technology (2012) from Linnaeus University, Sweden. He was awarded a Marie-Curie Fellowship in 2014 that was spent at Otto Schott Institute of Materials Research, University of Jena. He is the coordinator of the Solar-ERA.NET project LIMES – Light Innovative Materials for Enhanced Solar Efficiency. He is the author of more than 20 peer-reviewed scientific papers or technical reports as well as more than 10 oral or poster presentations at scientific conferences.
Increasing chemical resistance and improving mechanical properties of cover glass to PV modules
Christina Stålhandske, Karin Lundstedt, Peter Sundberg & Stefan Karlsson*
Glafo – the Glass Research Institute, PG Vejdes väg 15, SE-351 96 Växjö, Sweden
The cover glass of PV-modules constitutes a large part of the total weight of the unit. 3 mm glass is commonly used today. By improving mechanical properties of the glass the thickness could be decreased. The study is a part of the Solar-ERA.NET project LIMES where the aim is to improve the glassy materials used in PV modules.
Figure 1: Glass samples without aluminum oxide after final weathering procedure
Two series with 12 and 15 glasses, respectively, were studied in a DoE fashion. The chemical resistance was studied by P98 analysis and weathering experiments. Components found to improve the chemical resistance were alumina, zirconia, zinc, lanthanum and titanium oxide. Figure 1 shows some corroded weathered samples that did not contain alumina and Figure 2 shows changes in transmission before and after weathering of the float glass reference composition and modifications thereof. Nanoindentations have shown that zirconium oxide increases the hardness while magnesium and strontium oxide decreases it. Indentation fracture toughness, investigated with microindentation e.g. Figure 3, was found to be improved by magnesium, zinc, titanium and lanthanum oxide and decreased by barium and strontium oxide.
Figure 2: Transmission in the visual wavelengths before and after weathering, where N1 is the float glass composition reference and N3 and N8 are modifications thereof
Figure 3: An example of developed cracks during micro indentation
The findings resulted in a suggested composition for improving the properties of float glass by adding small amounts of zinc and titanium oxide as well as increasing the amount of aluminum and magnesium oxide.