Contact Energy shed 3000 electricity customers during December, but its gas and LPG customer numbers held steady.
The company had 464,000 electricity customers at the end of the December - 14,000 fewer than at the same period last year.
Total generation rose 0.5% to 851 gigawatt hours during the month. The national average electricity price rose slightly to $156.09 per mega watt hour.
The company says storage levels are above average in both the North and South Islands.