RWE npower commented that, while retail prices fluctuate more slowly than wholesale prices because energy companies traditionally manage risk by buying energy years in advance, the npower tracker would reflect the commodity cost of wholesale energy. It added that some elements of the tracker would remain fixed to provide a dampening effect.

Price comparison website, however, has warned that, although the tracker bill system will allow customers to benefit from lower wholesale prices before customers being charged on a standard tariff, the consumer would be hit with an increased bill much earlier should wholesale prices rise.

Geoff Slaughter, commercial manager of home services at, warned consumers to look at the tracker in detail and commented: In the light of decreasing wholesale energy prices, npower would have to implement a significant price reduction at the first opportunity to make its new product truly competitive.

Julia Lynch Williams, head of product management for npower was quick to explain: npower tracker is NOT for everyone but it will appeal to customers who want to follow the market more directly accepting the risks and the rewards.

She concluded: We’ve launched the first energy tracker because we wanted to bring some new thinking to the market. We are treating this as a pilot project and we will review the way the scheme has worked in March 2008 when this trial ends.