Duke Energy isn't saying whether it's a member of the American Legislative Exchange Council, known as ALEC, the conservative, state-level policy group that is a frequent target of the left.



The British newspaper The Guardian released internal documents last week that list Duke as a lapsed ALEC member. ALEC counts as members nearly one-third of North Carolina's Republican-led legislature, including House Speaker Thom Tillis of Cornelius, the documents show.



Duke won't confirm or deny being a member. Duke has supported ALEC's past events, including spending $50,000 to sponsor a 2012 meeting in Charlotte, and might do so again, says spokesman Tom Williams.



All six of the states in Duke's territory -- the Carolinas, Florida, Ohio, Indiana and Kentucky -- have Republican-majority legislatures, Williams notes, and five have Republican governors.



"It's all about having a seat at the table as discussions are held, and sometimes supporting things and sometimes not," Williams says.



Greenpeace and other groups say Duke's status matters because of ALEC's positions on renewable energy. Among them is a proposal that, critics say, would make it more expensive for owners of rooftop solar panels to pay utilities to use the electric grid.



"Duke's customers deserve to know whether their utility stands with an organization that plans to attack homeowners in North Carolina who have installed solar panels," Greenpeace researcher Connor Gibson said by e-mail. Duke's membership would "prove," he said that the utility supports the ALEC proposal.



ALEC lost support following the Trayvon Martin shooting in Florida last year for its support of "stand-your-ground" laws.



Dozens of bills introduced in the N.C. legislature this year, including measures on voter identification and private school vouchers, reflected the group's positions, Raleigh's News & Observer has reported.