Category: 🧱 Foundations
Complexity Level: ●○○○○ (Level 1 – Introductory)
Learning Level
You are currently viewing the Basic version of this topic.
Switch levels:
Basic:/basic/foundations/electricity-system-overview
Advanced: /advanced/foundations/electricity-system-overview
← Previous: Start of Foundations Section
→ Next Topic: Electricity Value Chain
Ontario's electricity system is the network of power plants, transmission lines, distribution systems, and control centres that generate and deliver electricity across the province.
Electricity must be produced and consumed at the same moment. Unlike many other commodities, electricity cannot easily be stored in large quantities. Because of this, the system must constantly balance supply and demand to maintain reliability.
The system is coordinated in real time by the Independent Electricity System Operator (IESO), which manages both the physical grid and the wholesale electricity market.
⚡ Electricity must be balanced continuously.
At every moment, the amount of electricity produced must equal the amount being consumed.
If supply and demand fall out of balance, the grid can become unstable.
Understanding the electricity system provides the foundation for understanding the entire energy sector in Ontario.
Nearly every activity in the sector—such as market operations, infrastructure planning, regulation, and policy—exists to ensure that electricity is delivered reliably and efficiently to consumers.
Participants across the sector rely on a shared understanding of how the system functions.
Examples include:
Electricity Grid
The electricity grid is the interconnected network of generation facilities, transmission lines, substations, and distribution systems that deliver electricity from producers to consumers.
Ontario's electricity system can be understood as four major components.
Electricity is produced at power plants using different energy sources.
Examples include:
Generation facilities convert energy into electricity that enters the grid.
Related topic:
Generation Types
Once electricity is generated, it must travel long distances across the province.
This is done through high-voltage transmission lines, which move large quantities of electricity efficiently between regions.
Transmission infrastructure includes:
Related topic:
Transmission System
Electricity is delivered to homes and businesses through local distribution networks operated by utilities known as Local Distribution Companies (LDCs).
Distribution systems operate at lower voltages and include:
Related topic:
Distribution System
Because electricity supply and demand must always remain balanced, the system requires continuous coordination.
The Independent Electricity System Operator (IESO) manages this process by:
Related topic:
Independent Electricity System Operator (IESO)
Electricity moves through the system in a sequence of steps:
Each stage of the system is interconnected and must operate reliably for the entire system to function.
Consider a summer afternoon when electricity demand is high due to air-conditioning use.
➡ Next Topic:
Electricity Value Chain
This topic explains how electricity moves through the system from generation to final consumption and introduces the roles of different participants in the electricity sector.
Last Updated: 2026-03-26