This is great news for Kiwis, as the increase in competition brings lower pricing to many customers' monthly power bills. If every New Zealander changed power companies to the cheapest one available to them, they could have saved a combined $307 million last year.

In 2015, up to 418,000 consumers changed their electricity supplier during the year - a record number. Carl Hansen, Electricity Authority chief executive, said the market was becoming increasingly competitive as consumers started to take more notice of what was available to them. The number of small, independent brands is growing rapidly, with their customer base up 12% from last year.

"While many of these retailers remain small, they are adding competitive pressure from the margins, which means the larger players need to keep innovating in order to maintain their market share," said Hansen.

Sue Chetwin, of Consumer NZ, welcomed the number of switches. "It does mean that people are thinking about their electricity retailer. More competition in the market seems to be prompting consumers to think about their bills."

On average, most New Zealanders are able to save $175 a year by shopping around for the cheapest power company.