Mighty River Power continued to lose retail customers, while gaining large additional volumes of commercial electricity sales in the year before its intended partial privatisation, figures released to the NZX show.
The state-owned power company issued its final quarterly update for the financial year to June 30, showing it shed 6,000 retail customers in the year to June 2012, down from 392,000 a year earlier to 386,000.
The update will be the last before the company makes its scheduled announcement of full-year profit on August 28, which is the earliest date by which a prospectus for the MRP part-sale can be issued, given legal restraints that prevent a prospectus being issued within the so-called "window" ahead of official results announcements.
The government has announced a timetable to sell up to 49 per cent of MRP by the end of the third quarter of this calendar year, although the timing looks likely to drift because of Maori challenges on water rights, and the offer's timing remains subject to favourable market conditions.
Prime Minister John Key announced further details of the float at his National Party's annual conference in Auckland over the weekend, including provisions intended to improve uptake by small-scale New Zealand investors.
These include a minimum parcel of $1,000 of shares, no scaling back for any retail investor seeking up to $2,000 of shares, and the promise of an additional share issue for long-term holders, with a likely three year threshold to qualify.
The update figures show sales to businesses and industry rose 29 per cent to 679 Gigawatt hours in the three months to June, compared with the same period a year earlier, and were up 13.5 per cent for the full year at 2,412 GWh.
Residential sales at 2,609GWh were down 1.6 per cent for the year, although the average price of electricity sold to customers on fixed price, variable volume contracts rose to $115.48 per Megawatt hour, up 4.6 per cent on the 2010/11 financial year.
MRP has been willing to lose retail customers in recent times after mopping up more of the residential market than intended during aggressive marketing campaigns in 2009 and 2010, including significant new customer bases in the South Island, where it was traditionally inactive because it has no South Island generation capacity.
The latest update highlighted "significant price separation between the North and South Islands influencing higher wholesale electricity purchase prices", as low hydro inflows to South Island lakes pushed up prices in the south. Constrained capacity on the Cook Strait capable made this worse by limiting total volumes of electricity capable of being sent from the North to the South Islands to compensate.
That saw wholesale electricity purchase costs rise 58.2 per cent from $47.44 per MWh on average in 2010/11 to $113.36 per MWh in 2011/12.
Total generation volumes for the year were 7,068GWh, up from 6,833GWh the previous year, although generation in the quarter under review was down 1,640GWh, reflecting high inflows to MRP's Waikato catchments the previous winter.
As a result, MRP used its Southdown gas-fired plant in Auckland more heavily in the latest quarter, producing 179MWh of electricity, compared with 33GWh in the same quarter a year earlier.
Geothermal production was flat at 556GWh, partially reflecting the impact of MRP selling a further 10 per cent stake in its Nga Awa Purua geothermal power station to its Maori joint venture partner.
The company's wholesale market position for the quarter was "slightly short" at 34GWh, the company said.
Meanwhile, Green Party leader Russel Norman attacked Key's bonus share proposal, suggesting that rewarding loyal local shareholders for holding onto their shares could cost taxpayers $200 million.
"If only a third of the shares were bought by retail investors and there was one free share for every ten bought, then that's a $200 million liability for the taxpayer...to the roughly 5 per cent of the population that the Government expects to buy shares directly."
Labour's state-owned enterprises spokesman Clayton Cosgrove said the proposal was akin to a "Ponzi scheme", leading Key to label Cosgrove "an idiot" in a Radio New Zealand interview.