On June 17, 2009 the California Energy Commission denied an application for a peaking natural gas-fired power plant in part because rooftop solar PV could potnetially achieve the same objectives for comparable cost. In a landmark decision, the CEC said:

"There is little difference between the COE of a 150-megawatt thin-film PV...and 100  megawattsof state-of-the-art gas turbine capacity at the same conditions. This is without considering the...renewable energy credits..., the elimination of air emissions, or the lack of dependence on a secure supply of natural gas."

Read about it here:
http://www.cadesertco.org/Natural_Gas_&_Electricity_Journal_2009_August.pdf