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Who We Are The Power System Demand & Price Conservation Electricity Pricing in Ontario


The IESO balances the supply of and demand for electricity in Ontario and then directs its flow across the province's transmission lines.

The Independent Electricity System Operator (IESO) works at the heart of Ontario's power system, connecting all participants - generators that produce electricity, transmitters that send it across the province, retailers that buy and sell it, industries and businesses that use it in large quantities and local distribution companies that deliver it to people's homes.

Every five minutes, the IESO forecasts consumption throughout the province and collects the best offers from generators to provide the required amount of electricity. This allows customers to see prices fluctuate based on supply and demand. As a result, they can shift consumption away from peaks in demand to times when the price is lower.

The IESO monitors the system and identifies what is required to maintain reliability in the future, reporting on these recommendations through regular publications. In its quarterly 18-month forecasts of the growth in demand for electricity, the IESO assesses whether there will be adequate generation and transmission facilities.

The IESO co-ordinates emergency preparedness for the province's electricity system and played a key role in managing the restoration of power following the August 2003 blackout.

The IESO continues to work with other stakeholders to evolve the market for the benefit of all. Further enhancements will strengthen the market, enhance reliability and provide Ontarians with greater access to information about their power system.

How the IESO is Governed

The Independent Electricity System Operator is a not-for-profit corporate entity established in 1998 by the Electricity Act of Ontario. It is governed by an independent Board whose Chair and Directors are appointed by the Government of Ontario. Its fees and licences to operate are set by the Ontario Energy Board and it operates independently of all other participants in the electricity market.

The IESO has full statute-based authority for establishing, monitoring and enforcing reliability standards in the province. All the companies that make up the power system in Ontario must meet the IESO's standards. An audit by the North American Electric Reliability Corporation cited the IESO as a model for system operators, while a peer review showed that its practices in enforcing reliability are exemplary.

IESO Vision


Power to Ontario.
On Demand.

Read more about the IESO's roles and responsibilities in managing Ontario's power system and operating the wholesale market.

The IESO’s System Control Centre is LEED® Silver certified for Existing Buildings: Operations & Maintenance.


LEED and the related logo is a trademark owned by the U.S. Green Building Council and is used with permission.