In this contribution we give an overview of the mechanisms behind degradation of Cu(In,Ga)Se-2-based modules. Based on the results from a detailed analysis of power losses in modules, prior to and after extended damp heat exposure, we discuss to what extent modules can be designed to achieve enhanced long-term performance. For conventional modules, we show that the stability can be improved by optimizing the interconnect and the front contact. Furthermore, we argue that gridded modules are better from a long-term performance point of view. A novel interconnect structure, specifically designed for long-term durability, is briefly discussed. (C) 2002 Elsevier Science B.V. All rights reserved.