California: When Will Rooftop Solar be the Same Price as Utility Power?

Rooftop solar supporters talk eagerly these days about the moment when it becomes as cheap to put solar panels on your roof as it is to just buy power from the local utility, thus spurring a blossoming of solar installations. That point is referred to as "grid parity," and for some places with expensive power -- Hawai'i, for example -- it's already here. Now, thanks to an interactive map produced by the Institute for Local Self Reliance (ILSR), you can explore when your state will reach grid parity, and the map offers some good news for Californians.

With the Solar Parity Map's controls, you can explore a range of scenarios including Federal incentive levels, artificially designated utility caps on solar, and the year. Each state is clickable, and a pop-up menu provides data for the scenario and year you've set.

And the good news is, most of the nation will reach grid parity well before 2020: in that year, assuming a 20 percent utility cap on solar and also assuming that Congress doesn't change the 10 percent tax credit that becomes law in 2017, more than 10 percent of the power consumed by both residences and commercial customers could be generated cost-effectively by solar in every state other than Washington, Idaho, and West Virginia. Nationwide, 343,790 megawatts of rooftop solar capacity could be feeding into the grid as or less expensively than power bought from the utility.

Grid parity, mind, isn't an all-or-nothing situation on a statewide basis. Different areas and different consumers will pay different prices for retail energy, and costs for installing solar will vary regionally and by consumer as well. It's all about percentages: once the amount of energy it's cheaper for a state to get from rooftop solar passes a certain point, then the rate of solar installations will likely explode -- unless artificial hindrances slow solar's growth.

The good news for California: much of the state has already reached the vicinity of grid parity, according to ILSR's mapping tool. In 2012, with a 30 percent tax credit in place, it was economically feasible for the state -- and more than a dozen other states, including Nevada, Arizona, and much of the Northeast -- to generate more than 10 percent of its residential and commercial electrical power use on rooftops.

Which means that disincentives to solar are all that's keeping California from moving faster toward its solar future.