But he said more Otago residents needed to switch power companies to save millions of dollars on their power bills and to maintain the competitive pressures on power companies.
Mr Hansen said Otago residents could save $162 a year, or $14.8 million collectively, on their annual electricity bill by changing their power company.
Otago residents who switched companies in 2011 could have saved up to $224 a year, he said.
The ''narrowing'' in savings to $162 a year revealed that power companies in Otago were becoming more price competitive and the What's My Number campaign had been effective since its inception in June 2011, he said.
''Our mandate is to promote competition so the prices the retailers charge reflect efficient costs.
"Unfortunately, at this stage, we don't have a great deal of visibility what the efficient costs is, but we do know the more competitive you make the market, the more incentive there is for them to price at efficient cost.
"If efficient costs are going up, then I think it's important that electricity prices go up, but when those costs come down, we also want to see the prices come down.''
The What's My Number website had 50,000 visits in its first three days and power companies lowered their prices, he said.
''We saw Contact Energy increase its discounts quite substantially. They said it was entirely attributable to our campaign that they lost so many customers and they increased their online prompt payment discount from 12% to 22% a few months later.''
Power company Powershop attributed its fast business growth to the campaign, he said.
''The anecdotal evidence is fairly strong it has had a big impact on the pricing behaviour of the retailers.''
New Zealand had 1.6 million residential connections and the campaign website had been visited more than 900,000 times, he said. However, a quarter of the visitors clicked through to the Powerswitch website to change their power company, he said.
Mr Hansen wanted more consumers to switch and ''take advantage of the savings'' and put more competitive pressure on retailers.
In Otago, the five cheapest power companies' prices were within 2% but some companies charged 10% more than others, he said.
The Electricity Authority received $3.5 million annually for the campaign and Consumer New Zealand received $1.5 million to promote the Powerswitch website.
The three-year funding cycle was due to finish in April 2014. A discussion paper on another possible campaign would target the elderly, rural residents and vulnerable people to switch power companies.
''People that haven't so readily taken up the message to shop around.''
