Photovoltaic modules have to withstand harsh environmental conditions during their service life. The chemical, electrical and mechanical properties of the module layer stack play a key role in this process. We offer high-resolution and highly sensitive layer analysis at all integration levels of PV modules. Module defects can then be traced back to the atomic level using transmission electron microscopy (TEM) after localization with electro-optical methods, which often provides the basis for understanding and eliminating the causes of defects. In addition, we are developing novel test methods for the evaluation of module degradation effects. For example, the in-house developed dust test chamber helps our customers to develop dust-repellent glass coatings. It makes it possible to realistically adjust the conditions under which dust "clings" to surface.