In addition, costs for fossil fuels may creep up due to raw material costs, shipping costs, and possibly carbon dioxide taxes. At an installed price of $1.25 per watt, the cost of PV solar is always cheaper than coal.At $2 per watt, it is cheaper after year 40. At $3.00 per watt, it is cheaper about year 80.n addition, costs for fossil fuels may creep up due to raw material costs, shipping costs, and possibly carbon dioxide taxes. At an installed price of $1.25 per watt, the cost of PV solar is always cheaper than coal.