New figures show the average cost of electricity for residential consumers has fallen for the first time in 15 years.
The figures supplied by the Ministry of Business, Innovation and Employment are for the year to the end of March.
They show customers collectively paid 1.4 percent less for electricity than in the previous year - mainly because of competitive offers made by suppliers seeking to retain or attract customers.
Companies have offered discounting incentives to sign up customers and reductions to reward prompt payment.
However, the ministry said prices will rise again, because of higher lines charges that took effect at the start of April.
The figures also showed more electricity was generated from renewable energy, while electricity derived from fossil fuels is down by 24 percent.