Most installers set the price according to the system's wattage, with a typical cost between $2.50 and $5 per watt. “Cost per watt” is a little like looking at the price per square foot when you buy a house. It helps you compare the value of solar energy systems in different sizes. In New Jersey, the average cost per watt is {average_cost_per_watt:state:NJ:2024}.