Contact Energy's result is likely to be disappointing, hit by low wholesale power prices, the loss of thousands of customers and the February earthquake in Christchurch.
Forsyth Barr analyst Andrew Harvey-Green said the past financial year had been tough and positives were "few and far between".
The company - 52 per cent owned by Australia's Origin Energy - will report its full-year result on Monday.
Profit was $154.7 million last year and this is forecast to fall to $148.9 million.
Harvey-Green said that while Contact would exceed ebitdaf (earnings before interest, taxation, depreciation, amortisation and financial instruments) guidance of about $430 million, it was the third year earnings had disappointed.