Itâs all part of how we stand up for customers every day at npower. You can rely on npower for your energy â weâre one of the UKâs biggest energy suppliers with the backing of one of Europeâs largest energy companies, the RWE group. We stand up for the community too.Weâre proud to have been a partner of Macmillan for 11 years raising over Â£3m.tâs all part of how we stand up for customers every day at npower. You can rely on npower for your energy â weâre one of the UKâs biggest energy suppliers with the backing of one of Europeâs largest energy companies, the RWE group. We stand up for the community too.