TrustPower, the smallest of the big-five electricity generator-retailers, is selling 8500 of its customers to its state-owned rival Mighty River Power.
The customers, all residential users in Auckland and Northland, will soon get their power bills from Mighty River's Mercury Energy brand. No price has been givenfor the sale.
TrustPower, which is based in Tauranga, last month told its 32,000 residential customers in Christchurch and Wellington that it no longer wanted to supply them with electricity, suggesting they move to Contact's budget brand Empower.
Contact is one of the only energy companies fighting for new residential customers, using its Empower brand to win business in areas dominated by traditional incumbent retailers.
State-owned generator-retailer Genesis last month announced that it had bought all 22,000 customers of Todd Energy's Freshstart brand.
TrustPower chief executive Keith Tempest said the sale to Mercury completed its "market rationalisation", under which the company had left residential markets where it could not offer competitive prices.
That allowed it to focus on markets where it already had a profitable retail presence.
"We have strong market presence in all of the 12 regions where we are the incumbent retailer, and in several other regions, and it makes sense for us to focus on those markets," said Tempest.
He said contracted commercial customers would not be affected by the sale of the residential consumers.
