An energy analyst representing consumers expects a report into the state of New Zealand's electricity market will show that power companies have been overcharging householders for years.
The report is part of a Commerce Commission investigation into alleged price fixing that began almost four years ago and is expected to conclude in the coming weeks.
The report, by Stanford University economics professor Frank Wolak, one of the world's top electricity industry analysts, is known to have probed more deeply into detailed power company records than any other.
Molly Melhuish, an analyst for the Domestic Energy Users Network, says it will be almost impossible for the Government not to act to bring prices down once the report's findings are released.
She expects the report will suggest more constructive answers than the use of price caps, which she says do not work.
Commerce Commission chief executive Nick Hill has declined to comment on the report, saying only that the investigation being conducted under part two of the Commerce Act has not been completed.
