What We Do

IESO control room operator at work

Operate the Power System in Real Time

The IESO balances the supply of and demand for electricity on a second-by-second basis and directs its flow across Ontario’s high-voltage transmission lines so it’s available to consumers when and where they need it.

Ensuring there is enough energy to meet Ontario’s 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 large and small generators, as well as storage technologies; transmitters and distributors who own and maintain the lines through which the electricity travels; and electricity consumers of all sizes, from residential to large industrial, who are increasingly able to respond to system needs and prices.

The reliability of Ontario’s power system benefits from being interconnected with neighbouring provinces and states in Canada and the U.S. The IESO works with system operators in these other jurisdictions to ensure energy adequacy and reliability across the northeastern part of the continent. These system operators work to develop enforceable standards for the reliable operation of their electricity systems while adhering to continent-wide standards.

Oversee Ontario’s Electricity Market

The IESO operates and settles the electricity wholesale market, 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 supports the effective participation in its markets and programs by a growing range of participants, including an increasing role for consumers.

By working closely with sector participants, the IESO works to foster an open, dynamic and sustainable marketplace that encourages new opportunities for innovation 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 auctions for capacity and demand response.

Street view of Richmond Hill, Ontario

Promote Conservation

Electricity conservation is crucial to meeting Ontario’s future energy needs, and the IESO is committed to developing clean, cost-effective alternatives to building new generation. In keeping with Ontario’s Conservation First Framework, the IESO coordinates province-wide conservation efforts that will reduce electricity consumption by 7.4 terawatt-hours (TWh) by the end of the year 2020 through energy efficiency programs delivered by Ontario's local distribution companies and the IESO. In addition, the IESO works with Ontario’s industrial, transmission-connected customers to achieve an additional 1.3 TWh by 2020.

These efforts include the Save on Energy suite of programs and incentives, targeted to both businesses and residents, and designed to expand the conservation market by supporting new technologies and services.

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. 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 Integrated Regional Resource Plans, specifically designed to meet the reliability requirements in each region across the province where an electricity need has been identified.

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, procurement and conservation efforts. The IESO is governed by an independent Board 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 Metering Data Management/Repository (MDM/R), which manages 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.