The energy supplier recorded a profit of £175 million, up £13 million on the same period last year, and said this was due to colder weather conditions at the start of the year.
In its interim results, Npower added this was “partially offset” by higher network costs and customers using less energy in the third quarter of the year.
The results also said that “the cost of the Energy Company Obligation (Eco) has also increased”.
The generation sector in the UK, which now forms part of RWE Generation, reported a “significant reduction in operating result”, posting a loss of £59 million in the first nine months of the year.
This was due to “unfavourable market conditions, particularly for gas plant”.
Overall, in the UK Npower and RWE’s UK generation businesses made an operating profit of £116 million, which is down 51 per cent year on year.
Paul Massara, chief executive at Npower, said: “Npower aims to make around 5 per cent profit in supplying energy to homes across Britain, but in the first nine months of 2013, we have made an average of £14, or 3.2 per cent, on a domestic customer account.”
He added that rising transportation, distribution, and government obligation costs have risen over the last year, and the company will focus on “keeping down the 16 per cent of a typical energy bill that we can control.”