The Electricity Authority has confirmed it will reset wholesale prices following a spike in March and has urged firms to take out cover to avoid being caught out in future.
The price surged to about $19,000 on 26 March following a planned maintenance shutdown in the upper North Island.
The authority ordered prices should drop to up to $3000 per megawatt hour.
It says the undesirable trading situation (UTS) threatened the integrity of the electricity market.
Although Genesis Energy was blamed for the high prices, the authority found it had not done anything wrong.
Some of those in favour of lower prices want the authority to go further to ensure a similar situation does not happen again, while its critics say the authority has rewarded bad business practice and exposed firms should have planned better.