Utility scale solar â which generally includes projects at 5 megawatts or higher â had a median price of $3.00 per watt for projects already completed in 2014, and $1.92 per watt for projects expected to be installed in 2013.Credit: Department of Energy / Lawrence Berkeley National Laboratory.arger utility-scale systems are projected to reach $1.30 to $1.95 per watt in that year. The cost per watt of a solar photovoltaic cell has fallen off a cliff in the last few decades, plunging 99 percent since 1977.