The IESO operates the province’s electricity grid 24/7, ensuring electricity will be available to all Ontarians when and where they need it. Achieving a reliable and cost-effective system depends on forecasting and monitoring demand for electricity through comprehensive planning processes that consider near-, medium- and long-term electricity needs, as well as coordinating the resources and services required to meet those needs.

Planning for Ontario's electricity needs comprises two processes: bulk system planning and regional planning.

Bulk system planning

Bulk system planning focuses on the electricity resources that transmit energy from the generation source to local distribution companies across the province. The IESO’s bulk system planning processes address provincial electricity needs and consider the impacts of various factors on the electricity system, including policy directions, the supply/demand balance, operability requirements and others.


Reliability Outlook

The Reliability Outlook guides operational planning in Ontario. The report presents Ontario’s demand forecast and associated drivers, resource adequacy projections and the assumptions that inform them, as well as an assessment of operability and the province’s transmission assets. Published quarterly, this Outlook provides insights over an 18-month planning horizon, extending the time frame an additional 42 months to five years biannually. Published every June and December, these extended versions address the drivers that can affect resource adequacy, and require the IESO to address associated reliability risks through outage management.  

Read the most recent Reliability Outlook and related documents


Annual Planning Outlook

The Annual Planning Outlook is a 20-year forecast for Ontario's electricity system and includes projected electricity demand, a resource adequacy assessment, transmission considerations, and performance indicators, and identifies the province's energy and capacity needs. The report provides these long-term adequacy requirements to inform investment and asset management decisions.

Learn more about the 20-year forecast for Ontario's electricity system

Regional Planning

Regional planning considers local electricity priorities within each of the province’s 21 electricity planning regions. This process considers each region’s unique needs, priorities and preferences. Options to satisfy local demand may include generation, transmission and distribution, and/or other innovative resources or solutions.

Get involved with power system planning for your region