Understanding the reliability of photovoltaic (PV) modules under field conditions is one of the primary areas to ensure prolonged operation. This article reported a study on assessing PV modules' reliability under different outdoor environments, using procedures available in the literature. We identified dominant failure modes of PV modules under different climatic conditions of India. Risk priority number (RPN) of different failure modes are estimated by analyzing the consequences of defects in performance and safety. Modules deployed under cold and sunny, hot and dry, warm and humid, and composite climates of India have more varieties of failure modes than those in cold and cloudy and moderate climatic conditions. The frequency of occurrences of benign or cosmetic defects of PV modules varies under different climatic zones. The biggest concerns in old PV systems were hot spots, internal circuitry discoloration, backsheet problems, and grounding wires' corrosion. In the hot zones, primary safety issues were frame grounding corrosion, backsheet problems, hot spots, and nonhot zones were backsheet burn marks, backsheet peeling, and grounding wire corrosion. The defects observed in different climatic zones were analyzed in terms of its possible defect generation route also.