Genesis, New Zealand's largest electricity retailer, says higher generation and prices drove a strong increase in profits.

The company, which has more than 660,000 gas or electricity customers, said net profits after tax in the year to June 30 were $90.25 million, compared to a loss of $16.6m in the previous year.

Earnings before interest, tax, depreciation, amortisation and other gains and losses (Ebitdaf), which reflects the underlying performance of the business, climbed 34 per cent to $392.65m.

Chief executive Albert Brantley said the company had managed to hold its leading position in the retail market.

"In a year of intense competition for electricity customers, we have held market share in the retail electricity market and experienced only a slight decrease in the retail gas market. We believe our focus on customer service and loyalty driven by product innovation is paying off," he said.

The group's revenue climbed 24 per cent to $2.27 billion as it generated more electricity and received more per unit, as wholesale prices climbed over winter.

''The improved financial performance was achieved against a backdrop of volatile wholesale electricity market conditions over the past year,'' Genesis said in a statement.

''The early part of the year was characterised by moderate water inflows, but the latter part of the year was characterised by low water inflows and resulting low hydro storage lake levels, before a return to near average storage at the end of the financial year as several large rain events at the beginning of winter impacted both the North and South Islands.''

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