But these certificates are largely insufficient to assert the actual long-term stability of these modules. Tests conducted by SCHOTT Solar under extreme conditions revealed drastic differences. The backing sheet of a photovoltaic (PV) module is one of the critical areas. They all look the same if you take a superficial glance. Standard modules are generally manufactured using white, opaque backing sheets, as they provide the best protection against heating up and therefore ensure that solar cells achieve high-efficiency levels.

The backing sheet is something like the skin of a module, protecting it against damage and insulating it to the outside. If backing sheets are damaged, dampness can seep in and trigger gradual corrosion processes. In the worst case, the sheet no longer provides insulation, which means that there is the danger of electric shock from the frame or the mounting construction of the PV module.

In more than 50 years of manufacturing, SCHOTT Solar has gained specialist insights into test procedures and material qualities. It conducts systematic test routines on backing sheets to ensure that these will last for 25 years and longer without sustaining any damage. Any manufacturer aiming to provide consistently high quality levels will find that there is no alternative to conducting one’s own tests. The reality is that each manufacturer assembles modules from an individually selected range of components, which can vary considerably.

As a result, considerable differences in material ageing can arise even under the same weather conditions. In SCHOTT Solar’s test lab in Alzenau, Germany, backing sheets are subjected to a two-tiered test routine, which tests the performance and stability of modules with any given backing sheet.

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The company voluntarily conducts tests on its modules in its own climate test chambers, which are twice as taxing as demanded by the International Electrotechnical Commission standard. SCHOTT Solar's customers are increasingly focusing on long-term stability. The company’s tough test conditions are determining how to ensure the quality of its modules today and in the future. Only three of SCHOTT Solar’s candidates in our climate tests as well as additional test routines prescribed by International Electrotechnical Commission met the company’s product specifications.

The results, materials data and test values collected during tests are compiled in a database, making them available to researchers during future tests and providing yet another example of the company’s quality standards.

To find out more, visit www.schottsolar.com