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Market Information


IESO Information

The Independent Electricity Supply Operator (IESO) is an independent, non-profit organization that is responsible for the day-to-day operations of Ontario’s electricity system. The IESO ensures there is adequate electricity for consumers at all times, including importing as required.

During periods of peak demand when supplies of reserve power are low, the IESO may issue public appeals for consumers to reduce consumption. Any reduction in transmission or generation availability or any increase in demand could create shortfalls of electricity and require action such as voltage reduction on the province-wide system. Reduce consumption requests are usually issued during the summer months, when air conditioners are turned up to combat heat and humidity.

For more information regarding the IESO and its functions, visit, or contact them at 1-888-448-7777.

Electricity Facts

Ontario’s System-Wide Electricity Supply Mix: 2017 Data

Electricity Retailing – Disclosure to Consumers, O. Reg. 416/99, requires retailers to disclose to consumers the Ontario system-wide electricity supply mix in the manner established by the Ontario Energy Board. The Board’s Directive for the Disclosure of Information to Consumers by Electricity Retailers under Ontario Regulation 416/99 prescribes the manner and timing requirements for this disclosure. The Directive applies to all retailers, including distributors that provide standard supply service.
Under O. Reg. 416/99 the Ministry of Energy is responsible for providing Ontario’s electricity supply mix data for electricity suppliers. The following label discloses the system-wide electricity supply mix data for 2017. This data must be used by electricity suppliers for the purposes of complying with the disclosure obligations of O. Reg. 416/99 and the Directive. This data should be considered current until further notice.

Electricity sources Ontario’s Electricity Mix *
Water power 25.6 %
Alternative power sources 9.8 %
– solar 2.2 %
– wind 7.2%
– biomass 0.4%
– waste 0%
Nuclear Energy 60.1 %
Natural Gas ** 4.0 %
Other 0.3 %

* Includes both transmission and distribution -connected/embedded generation
** Includes duel-fuelled facilities that are predominantly natural gas ( e.g. Lennox Generating Station)
Note: Figures may not add to 100% due to rounding.