Quick answer: A modern residential solar panel measures roughly 66–82 inches long, 40–45 inches wide, and 1. 6 inches thick, weighs 40–55 lb, and produces 350–460 watts. The full size-by-wattage. Panel “Size” vs Physical Dimensions: The most critical distinction for homeowners is that solar panel “size” refers to electrical output (measured in watts), not physical measurements. A 400W panel has the same physical footprint whether it produces 350W or 450W – the difference lies in cell. Large-format photovoltaic panels are designed for industrial and commercial installations, where maximizing energy production over large surfaces is the priority. The most common sizes for these panels are 200 x 110 cm or larger. Typical dimensions are about 1650 mm tall by 990 mm wide (roughly 65 x 39 inches).