Accurate evaluation of the durability of photovoltaic modules is a critical need for investors, manufactures, insurers, and customers. Accordingly, researchers around the world have sought sequential- and combined-accelerated stress testing to better predict potential field failures [1-4]. A framework for such testing has been developed and put into practice in the DuraMAT project with principles of (1) maximizing the representation of the sample under test toward that of the shipping design, (2) including the stress factors that occur in the natural environment, and (3) applying these stresses in field-relevant levels and combinations. NREL’s solution for combined-accelerated stress testing (C-AST) applies the factors of light, humidity, temperature, mechanical and system voltage stress. Applying such accelerated testing that comprises diurnal and seasonal stress cycles, degradation mechanisms including solder bond failure, light- and potential-induced degradation, backsheet cracking, delamination, corrosion, cell cracking, and connector failure could be observed depending on the weaknesses of the module under test. Confirmation of the field-relevancy of the degradation modes could be established based on materials analysis and acceleration factors were determined for some observed degradation mechanisms. With such approach, faster time to market of new technologies, bankability, and lower risk and cost for PV can be realized.