Photovoltaic solar power in the US, 2000 to 2015. "Non Residential" means commercial installation, like on the roofs of warehouses. Quite a graph, no? And costs continue to fall rapidly. Back in 2011, the Energy Department set a goal of $1/watt for constructing utility plant solar power as the point at which it would be competitive with natural gas, even without subsidies. In 2011 the cost was typically about $2/watt. Right now it is about $1.15/watt, and utilities predict they will be building plants for less than $1/watt in 2017. That's a 50% drop in six years.