While grid electricity prices have increased by an average of 2% every year since 2006, solar cost has been reduced by an average of 10% a year. As a result, by 2021, nearly 100 million Americans will be able to use solar energy without subsidies, at less than grid prices. For this to happen, we must rethink electricity policy and plan ahead.Grid parity does not only mean that solar will become affordable to many, but also that Americans will transform from energy consumers into producers, and will give them a stake in electricity production and energy policy. Each house with a solar rooftop has (on average) two voters who will strongly support smart solar policies. And when half of Americans can install solar for less than the cost of grid electricity, it makes a majority that favors local ownership of localized energy production long before solar power becomes a significant portion of total electric generation.[/caption]
A major technical roadblock to realizing the full potential of solar grid parity is the so-called 15% rule, a common state regulation that limits the amount of solar on a utility's distribution grid to 15% of the peak demand. However, recent research shows that the 15% rule is too conservative, and that there are minimal impacts when distributed solar supplies 25% or more of the power to the local electricity grid.
The best transition policy may be a feed-in tariff, as is used in solar-leading countries like Germany.