However, system prices continued to fall, despite the lack of installation growth. Driven by significant reductions in balance-of-system costs, the cost for a medium-scale commercial system averaged $2.25 per watt by the end of 2014. This is down from $2.53 per watt in the first quarter of 2014.owever, system prices continued to fall, despite the lack of installation growth. Driven by significant reductions in balance-of-system costs, the cost for a medium-scale commercial system averaged $2.25 per watt by the end of 2014. This is down from $2.53 per watt in the first quarter of 2014.