Genesis Energy has responded to claims it was price-gouging when electricity prices skyrocketed in late March.
Prices soared after transmission into Auckland from the south was impaired by long-scheduled maintenance on lines run by Transpower, the national grid operator.
During the outage, some Genesis prices reached $20,000 per megawatt hour, four times crisis levels and 200 times average prices nationwide.
In a draft finding, the Electricity Authority found the electricity market was not functioning properly and ordered the prices to be lowered.
But in a counter-submission published on Friday night, Genesis says the fault lay not with itself but with other companies, which failed to prepare for a scheduled and long-advertised outage.
If the authority's verdict stands, Genesis says, similar errors will be encouraged in future. It says normal trading was not threatened in any way and Genesis did not engage in manipulative, misleading, unlawful or undesirable conduct.
Other companies have made submissions; a final verdict is expected in June.