How much do solar panels cost in Litchfield Park, AZ? The average cost of solar panels in Litchfield Park, Arizona is $14,350. Costs ranged from $12,198 to $16,502 in 2018-2019 according to EnergySage. These costs do not include the Federal Investment Tax Credit of 30% or other local incentives. The average payback period for solar panels in Litchfield Park took 7.62 years and the average electricity savings from solar panel installation was $49,166 over a 20 year period. The average cost per watt is about $2.87 a watt. This study included installation of a 5kw solar system, a slighty smaller than the average system size.