The Nevada Public Utilities Commission approved a deal that would restore older, more favorable rates to about 32,000 customers who installed or applied for a rooftop solar system before this year.
The commission signed off on a settlement between NV Energy, SolarCity, the state Bureau of Consumer Protection and the commission's staff.
Customers who signed up before a rate hike took effect this year are now "grandfathered" into lower rates for 20 years.
Commissioners raised rates for rooftop solar customers this year, saying it corrected a subsidy that non-solar customers were paying for those who had panels.
Solar companies that wanted to reverse the ruling failed to get a repeal measure on November's statewide ballot, and have since settled on the regulatory solution.