Meridian Energy has made a record first half profit with improved revenue.
The South Island generator's net profit for the six months ended December rose 26 percent to $191 million.
Revenue was up 5 percent to $1.78bn on record hydro generation from the South Island lakes.
It had significant customer and sales volumes growth across all segments, including 39 percent growth in corporate sales.
"Customer numbers across New Zealand and Australia have grown 8 percent since June 2019," chief executive Neal Barclay said.
Meridian was also in talks with its largest customer, Rio Tinto, which was conducting a strategic review of its aluminium smelter at Tiwai Point, expected to be completed by the end of March.
It said it had offered Rio Tinto a change in their supply contact.
It also noted that the smelter might recieve lower transmission costs in the future as a result a review last year.