The volume of a prism is the product of the area of the base and the distance between the two base faces, or the height (in the case of a non-right prism, note that this means the perpendicular distance).
In 2017, most homeowners are paying between $2.87 and $3.85 per watt to install solar, and the average gross cost of solar panels before tax credits is $16,800. Using the U.S, average for system size at 5 kW (5000 watts), solar panel cost will range from $10,045 to $13,475 (after tax credits). Thatâs nine percent lower than it was a year ago, and solar panel system costs are continuing to fall.
1 Metal roofs cost anywhere from $3 per square foot to $20 per square foot or more (or $4,500 to $30,000 for a 1,500 square foot roof). 2  Aluminum roofing costs $6 to $12 per square foot ($9,000 to $18,000).  Steel roofing costs $3 to $10 per square foot ($4,500 to $15,000).