Meridian Energy said its net profit gained 19 per cent to $315m in the first half thanks to positive changes in the value of its hedging arrangements.
At an operating level, its earnings fell by nine per cent to $422m due to lower hydro generation in New Zeland and lower market prices in Australia.
Separately, Meridian said it would soon begin construction of a new $395m wind farm in Hawke's Bay.
Harapaki will be New Zealand's second-largest wind farm with 41 turbines generating 176 MW of renewable energy, enough to power over 70,000 average households.
The wind farm in Hawke's Bay was deferred last July due to NZAS announcing its intention to exit New Zealand.
"But given that NZAS has agreed to a four-year exit deal, Meridian is now confident that Harapaki will support our business's growth plans," the company said.
In its result, chief executive Neal Barclay says Meridian's performance partly reflected less than favourable conditions compared to the prior year.
Overall, hydro generation volumes were down seven per cent due to lower starting storage and lower inflows since October 2020.
"Generation volume and price volatility area feature of New Zealand's hydro-based renewable electricity system; however the underlying performance of the business remains strong and we were particularly pleased that the strength of the Meridian and Powershop brands continued to shine through," he said.
Customer numbers across New Zealand and Australia now exceed half a million and have grown 3 per cent since June 2020.
Meridian declared a 5.7c interim dividend, unchanged from the previous corresponding period.
The company, New Zealand's second biggest by market cap, is just over 51 per cent-owned by the New Zealand Government.
US investment giant BlackRock has seven per cent after its renewables-focused exchange-traded funds (ETF) picked up stock last year and early this year.
Meridian's shares last traded at $5.62, compared with $9.40 at the peak of ETF buying early this year.
In January, Rio Tinto, the majority owner of Meridian's biggest customer, NZ Aluminium Smelters (NZAS), announced that it had put off closure of the Tiwai Point plant from August this year to 2024.
"The additional four years of smelter operation will be invaluable to the Southland region as it allows time to create new business opportunities and new jobs for Southlanders."
"Meridian is committed to working with a range of parties who are progressing some exciting new opportunities in Southland, from mega-scale data centres to hydrogen production at scale," Barclay said.
Barclay said the electricity sector was a huge part of the solution to decarbonise the economy.
"Our decision to build the new Harapaki wind farm is our next step towards that solution," Barclay said.