Most solar panels operate most efficiently around 77°F (25°C), but on hot summer days, surface temperatures can exceed 150°F (65°C). While your system still generates energy, extreme heat can slightly reduce efficiency during peak afternoon hours. Answering the inquiry regarding indoor solar energy during the summer yields several critical insights. Energy production is at its peak during summer. With. Whether you're motivated by rising utility costs, a desire for energy independence, or the appeal of clean, renewable power, this guide will walk you through why summer is an ideal time, the costs involved, incentives, and tips on how to choose the right system and get started.