When utilities around the country have wanted to build fossil-fuel plants, defeat energy-efficiency proposals or slow the growth of rooftop solar power, they have often turned for support to a surprisingly reliable ally: a local chapter of the National Association for the Advancement of Colored People.

In 2014, the top officials of the N.A.A.C.P.’s Florida division threw their organization’s weight behind an effort to stymie the spread of solar panels on residential rooftops and cut energy efficiency standards at the behest of the energy industry. The group’s Illinois chapter joined a similar industry effort in 2017. And in January 2018, the N.A.A.C.P.’s top executive in California signed a letter opposing a government program that encourages the use of renewable energy.

Most Americans know the N.A.A.C.P. as a storied civil rights organization that has fought for equal access to public facilities, fairness in housing and equality in education. But on energy policy, many of its chapters have for years advanced the interests of energy companies that are big donors to their programs. Often this advocacy has come at the expense of the black neighborhoods, which are more likely to have polluting power plants and are less able to adapt to climate change.

The activities of the N.A.A.C.P. chapters, which operate with significant autonomy, have so unnerved the group’s national office that it published a report titled the “Top 10 Manipulation Tactics of the Fossil Fuel Industry” in April. It is also sending its staff to state and local chapters to persuade them to fight for policies that reduce pollution and improve public health even at the risk of losing donations from utilities and fossil fuel companies.