By Jonathan Stempel

(Reuters) - Thousands of rooftop solar energy customers in Nevada are expected to be grandfathered into older, more favorable rates for 20 years under a settlement between Elon Musk's SolarCity Corp <SCTY.O> and the NV Energy unit of Warren Buffett's Berkshire Hathaway Inc <BRKa.N>.

Both companies on Tuesday confirmed the settlement, which is scheduled for a vote on Friday by Nevada's Public Utilities Commission.

The accord would shield roughly 32,000 customers who installed or applied to install rooftop solar before this year from new charges and reduced subsidies that the PUC had approved last December.

"This agreement is a victory not only for 32,000 solar customers in Nevada, but also for all Americans who expect these investments to be protected," Jon Wellinghoff, SolarCity's chief policy officer, said in a statement.

NV Energy had supported the new rates, saying the old rates forced its customers to subsidize those who favored green power.

But it later asked regulators earlier this year to implement the grandfather clause.

In a statement on Tuesday, NV Energy said its proposal was intended to "offer a solution" for solar customers "in the most efficient and timely manner."

Governor Brian Sandoval also supported the accord, after asking the companies to come up with a solution.

"I am hopeful that the PUC will act quickly on this agreement," he said in a statement. "It is time to move on."

At Berkshire's annual meeting on April 30, Buffett expressed support for NV Energy's original position.

"I personally think that if society is the one that's benefiting from the reduction of greenhouse gasses, that society should pick up the tab," he said.

(Reporting by Jonathan Stempel in New York; Editing by Alan Crosby)