Planning the Electricity System

The IESO plans the electricity system to ensure Ontario’s energy needs are met. This includes coordinating the construction of transmission lines and facilitating the development of new power plants. Broad and effective engagement with communities and partners is necessary to balance the needs of homes and businesses with the overall needs of the electricity system.

Map of the regional network for Ontario

Regional Planning

Ontario is divided into 21 regional planning zones that each undergo a five-year regional planning cycle. Regional planning looks at the electricity needs of each region, considering energy conservation, electricity generation, distribution infrastructure and innovation to meet those needs.

Visit the Regional Planning web page to learn more.

Three Levels of Electricity Planning

  • Provincial Planning: Provincial electricity planning, referred to as bulk planning, focuses on province-wide needs. Bulk planning considers the location of large power plants, the capacity of high-voltage transmission lines and Ontario’s grid connections with neighbouring jurisdictions.
  • Regional Planning: Ontario is divided into 21 regional electricity planning zones. The IESO assesses each zone’s electricity needs during the regional planning process, considering energy efficiency, electricity generation, infrastructure and opportunities for innovation. The IESO leads the regional planning process, working closely with Local Distribution Companies (local hydro companies) and transmitters.
  • Local Planning: Electricity is delivered directly to households and businesses across Ontario by Local Distribution Companies (LDCs), or local hydro companies. More than 60 LDCs are actively involved in forecasting and planning for their communities’ energy needs and maintaining local electricity infrastructure. The IESO is not responsible for local planning, but the work of LDCs is integrated into broader regional planning efforts.
Autumn trees with a road leading to a city.

Annual Planning Outlook

Provides a 20-year overview and assessment of Ontario’s electricity system and its ability to meet demand.

Read the Annual Planning Outlook

Two transmission line towers and a blue sky.

Reliability Outlook

Reports on the ability of Ontario’s electricity system to meet demand over the next 18 months.

Read the Reliability Outlook

Hydro generator, lake and forest.

Resource Adequacy Framework

Sets out a long-term competitive strategy to acquire resources.

Learn about the Resource Adequacy Framework

Securing New Energy Supply | The Evolving Grid

The IESO secures a supply of electricity in the short, medium and long term to ensure that the operation of Ontario’s electricity system remains reliable, affordable and sustainable.