The Ontario Energy Board has found that a Brampton natural gas plant "gamed" the system out of nearly $100 million, costs borne by ratepayers.
A report from the OEB's market surveillance panel, quietly posted online last month, concluded that Goreway Power Station repeatedly exploited defects in the system over several years.
It says the systems in place create opportunities for exploitation, to the serious financial disadvantage of ratepayers, and Goreway's conduct offers a clear illustration of those flaws.
The OEB says Goreway agreed to a settlement with the Independent Electricity System Operator to repay a "substantial portion" but the amount is blacked out in the report at Goreway's request.
The company was also fined $10 million, but it said through a lawyer in a letter attached to the report that it disagrees with many of the conclusions, including suggestions that Goreway gamed the system or deliberately misled the IESO.
Energy Minister Glenn Thibeault says the IESO discovered the issues with Goreway early on and senior leadership at the company have since been replaced.