Profit at the country's biggest power retailer, Genesis Energy, has fallen sharply because of reduced values for the contracts it uses to guard against volatile power prices.
Genesis's net profit for the year ended June fell 83 percent to $20 million from last year's $119m, but its underlying earnings, which excludes the one-off items, were up 8 percent and at the top end of the company's forecast range.
Chief executive Marc England said the result showed the benefit of having different types of power generation, which was spread throughout the country, as well as other interests in gas production.
"Over the fiscal year we have created a multi-fuel, single service platform to support our yield plus growth investment proposition."
Genesis generated more power at better prices from its mix of hydro stations and the gas and coal fired Huntly station, which it fires up to meet shortfalls in hydro and renewable generation.
It also has a major stake in the Kupe gas field and also has an LPG business.
Genesis has more than half a million customers in all markets, down about 2 percent on the year before, with losses in its electricity business, where profit margins also eased marginally.
But it gained customers for its LPG business, and the number of customers buying more than one fuel also rose.
It forecast operating earnings for the coming year broadly the same as the year just gone.
The full year dividend was increased slightly.