B-class solar panels can typically function efficiently for 20-25 years or even longer, depending on various factors such as quality of materials, maintenance, and local weather conditions. 1, The lifespan of B-class solar panels is influenced by their construction and the. Solar panels come with 25-year performance warranties and are often described as lasting "25 years. " In practice, many panels from the 1990s are still generating electricity today — suggesting the real lifespan may be significantly longer than the warranty period. average lifespan typically ranges from 25 to 30 years, 2. performance degradation over time, 3. environmental influences, and 4. Learn how degradation rates, warranty terms, and installation quality affect how long your system produces power. A panel doesn't simply stop working on its. Most modern panels degrade at a rate between 0.