What We Do

IESO control room operator at work

Operate the Power System in Real Time

The IESO ensures the reliability of the province’s power system, balancing the supply of and demand for electricity on a second-by-second basis and directing its flow across high-voltage transmission lines so it’s available to Ontarians when and where they need it.

Ensuring there is enough energy to meet demand 24 hours a day, 7 days a week, is highly complex and requires close coordination of the many parts that make up the system. These include generators, transmitters and distributors who own and maintain the lines through which the electricity travels, and electricity consumers of all sizes.

The IESO works with its Canadian and U.S. neighbours to maintain continuous reliability of our interconnected North American power grid. In addition to contributing to the development of enforceable standards, the IESO is the first system operator in North America to be accountable for leading the sector on cybersecurity matters.  

Oversee Ontario’s Electricity Market

The IESO operates and settles the wholesale electricity markets, where the market price is set based on accepted offers to supply electricity against the forecasted demand. The IESO works to ensure that the information and services it provides support the effective participation of a growing range of market participants, including consumers.

By working closely with sector participants, the IESO aims to foster an open, dynamic and sustainable marketplace that encourages new opportunities for emerging resources and increased value for consumers. To this end, the IESO supports the development of flexible and cost-effective market-based solutions for managing Ontario’s future electricity system needs, including the annual auctions for capacity.

Street view of Richmond Hill, Ontario

Delivering Energy Efficiency

The IESO’s energy-efficiency and demand-management programs are continuing to demonstrate that they can play a critical role in meeting Ontario’s future energy needs, serving as a viable resource and delaying the need for new infrastructure. In keeping with Ontario’s goals with respect to reducing long-term energy costs, the IESO supports business and industrial energy-efficiency programs – and the impact has been far-reaching. Since Save on Energy was first launched a decade ago, Ontario has achieved 16 terawatt-hours  of energy savings, enough to power over 1.8 million homes for a year. These efforts include the Save on Energy suite of programs and educational resources, which help to make homes more liveable and businesses more competitive.

Plan for Ontario’s Future Energy Needs

The IESO plans for the resources needed to meet Ontario’s future electricity needs. It forecasts and assesses the province’s current and short-term electricity needs, as well as the adequacy and reliability of the integrated power system.

For the longer term, the IESO forecasts energy demand up to 20 years to ensure Ontarians have sustainable solutions well into the future. The IESO competitively procures a wide range of electricity resources and services to address those needs.

It is also specifically charged with creating integrated regional plans that allow for more customized approaches to meet evolving electricity needs throughout the province.

Stakeholder Summit 2015

Engage Our Stakeholders, Communities and Customers

In planning Ontario’s electricity needs, the IESO engages with stakeholders, communities and customers to ensure that both province-wide energy needs and community-level requirements are being met. The IESO strives to provide information that is timely, relevant and available to all and encourages participation from all interested parties. In recent years, the IESO has worked closely with transmitters and distributors, as well as municipalities and First Nations and Métis communities to develop plans to meet the specific reliability needs of particular regions.

Learn about opportunities to get involved.


The IESO is a not-for-profit corporate entity established in 1998 by the Electricity Act of Ontario. On January 1, 2015, through amendments to the Electricity Act, the IESO merged with the Ontario Power Authority (OPA) to bring together real-time operations of the electricity grid and long-term planning, competitive procurement and energy-efficiency programs. The IESO is governed by an independent Board of Directors, with a Chair and Directors appointed by the Government of Ontario. All fees and licences to operate are set by the Ontario Energy Board, and the IESO operates independently of all other participants in the electricity market.

Smart Metering

As Ontario’s designated Smart Metering Entity (SME), the IESO is responsible for the implementation and operation of the province’s meter data management/repository (MDM/R), which helps manage consumption data for residential and small business smart meters. With nearly five million smart meters, supporting  more than 60 local distribution companies, Ontario’s MDM/R is one of the largest shared systems in the world, and provides a province-wide, cost-effective solution for the processing, storage and protection of the electricity consumption information local distribution companies use to bill their customers.