Solar photovoltaic (PV) systems have become a cornerstone of the global energy transition, deploying at a rate unmatched in modern energy history. Yet the climate gains expected from solar are increasingly compromised by regionally uneven degradation-a risk too often sidelined in planning and policy. Capacity may be surging, but swings in temperature and humidity, ultraviolet exposure, and extreme weather steadily erode output and shorten service life, undermining emissions-reduction goals. The sources of decline differ starkly by climate: in arid regions, panels deteriorate under relentless heat and ultraviolet (UV) exposure, while in humid, tropical zones, moisture ingress and electrochemical corrosion prove more destructive. These disparities make clear that a one-size-fits-all deployment strategy is untenable. Regional climate variability shapes not only the pace but also the pathways of degradation. Our review examines how material properties and environmental stressors interact to accelerate power loss, and sets out a framework for climate-resilient design that balances technical feasibility, economic viability, and environmental adaptability. The imperative is unambiguous: energy policy must embed "degradation awareness" if solar systems are to deliver reliably on global decarbonization goals.