Council-owned Robin Hood Energy has made a trading surplus three years after launch, and notched up 115,000 customers.
The not-for-profit company said it would use the £202,000 to voluntarily enter the Warm Home Discount scheme, which helps older people and those on low incomes to pay their fuel bills.
Small suppliers are exempted from schemes including the Warm Home Discount until they reach 250,000 customers, a source of irritation for larger suppliers who claim it enables smaller rivals to undercut their tariffs.
The company said it will also procure all of its energy from wind and solar power.
Robin Hood Energy chairman Councillor Steve Battlemuch said operating a trade surplus after three years was “a big achievement”, suggesting most energy companies “take at least five years to reach this stage”.
“I genuinely believe Robin Hood Energy is proof that a new generation of ethical, publicly owned companies can offer an alternative to the Big Six,” he added.