A typical 100-watt solar panel is 41.8 inches long and 20.9 inches wide. It takes up 6.07 sq ft of area. If you have a 1000 sq ft roof, and you can use 75% of that roof area for solar panels, you can theoretically put 123 100-watt solar panels on a 1000 sq ft roof.
[pdf] Individual solar panels come in a lot of different shapes and sizes, but generally speaking, they're about 3 feet by 5 feet, or about 15 square feet per panel, according to Pamela Frank, vice president of Gabel Associates, an energy consulting firm.
[pdf] Most residential solar panels are 1.7m tall x 1.0m wide (or 1.7 m2), with a maximum power output of around 330W. Solar panels also come with 72 solar cells, which are larger to accommodate the additional cells.
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