Duke Energy Corp., one of the nation’s largest electric utility providers, has taken a majority stake in Irvine-based Phoenix Energy Technologies.

Terms of the deal were not disclosed.

Phoenix Energy makes software that helps companies manage energy usage, including across several buildings without additional hardware.

It will continue to operate independently with its established management team, the company said.

Lisa Varga founded Phoenix as a consulting firm in 2004 in New Jersey and relocated the company to Irvine when she refocused the business model on technology.

Its customers have included Office Depot, the Home Depot, Cinemark Theatres, Bed Bath & Beyond, and Best Buy. Phoenix Energy has been on the Business Journal’s annual lists of fastest growing private companies and best places to work. It posted revenue of about $4.8 million in the 12 months through June 2014 and had about 60 employees at the time, according to the latest figures compiled by the Business Journal.

Charlotte, N.C.-based Duke Energy posted sales of $23.9 billion last year and has about 7.3 million customers in six states in the Southeast and Midwest.

Duke’s shares are up 1.6% in afterhours trading to a market value of about $51.7 billion.