Even though every panel is rated out to 20 to 25 years, that does not mean they are all necessarily equal, nor will a panel developed for use in warm, arid areas be the best choice in the colder Northern climates:
Manufacturers can differentiate themselves from their competitors and optimize their module designs for the intended applications, according to a paper summarizing the efforts, “Three-Prong Path to Comprehensive Technical Standards for Photovoltaic Reliability.” Modules built for heavy snow may need not only thicker glass but heavier-duty frames and support rails, all of which increase upfront costs. But money may be saved in the long run by the manufacturer who differentiates, building a hardier module for the most difficult climates and a slimmed-down, less expensive module for milder climates.