Independent Electricity System Operator

The Independent Electricity System Operator (IESO) works at the heart of Ontario’s power system, connecting all participants – generators that produce electricity, transmitters that send it across the province, retailers that buy and sell it, industries and businesses that use it in large quantities and local distribution companies that deliver it to people’s homes.

Every five minutes, the IESO forecasts consumption throughout the province and collects the best offers from generators to provide the required amount of electricity. This allows customers to see prices fluctuate based on supply and demand. As a result, they can shift consumption away from peaks in demand to times when the price is lower.

The IESO monitors the system and identifies what is required to maintain reliability in the future, reporting on these recommendations through regular publications. In its quarterly 18-month forecasts of the growth in demand for electricity, the IESO assesses whether there will be adequate generation and transmission facilities.