It is widely accepted that adherence (which reports to what is measured when performing an adhesion test) of the encapsulant to the main substrates of the module plays a key role in the long term reliability of the PV module [1,2]. Consequently, adherence is commonly measured and used to assess or compare encapsulant compatibility with a given substrate. The most common procedures used in the PV field to characterize adhesion between a polymer film and a substrate are the so called peeling test, lap shear and compressive shear tests. Here we use a compressive shear setup to characterize the adherence of Poly Vinyl Butyral (PVB) and Polyethylene-covinyl acetate (EVA) to glass before and after degradation in damp-heat (DH) conditions (85°C, 85%RH). The adherence metrics that can be derived from a Compressive Shear Test (CST) are presented and discussed. We show that a single metric is not sufficient to characterize adherence and that a set of at least two indicators including the peak shear stress and the viscous dissipation should be used. Using this set it is found that the interface PVB/Glass is more affected by the degradation than the EVA/Glass interface.