Preparing for Ontario’s Summer Peaks: Guidance for Class A Customers

The 2025 peak-setting period began May 1. Class A customers participating in Ontario’s Industrial Conservation Initiative (ICI) will have their Global Adjustment (GA) charges set based on their electricity demand during the top five peak hours between May 1, 2025, and April 30, 2026.

These five hours are not announced in advance. Participants need to monitor grid demand and respond accordingly. Mismanaging peak hours can result in significantly higher GA charges over the next billing year.

What to Do Now

1. Confirm Your Class A Status: Utilities issue Class A eligibility notices in May If you're eligible, you must opt in by your local utility’s deadline (usually mid-June). Customers near the 1 MW average monthly demand threshold should reassess whether participation is beneficial this year.

2. Review and Test Your Curtailment Plan: Facilities should have a defined process to reduce demand during potential peaks. This includes identifying which loads can be shut down, sequencing equipment properly, and verifying internal coordination. Simulations or test events are recommended. Your curtailment plan may vary depending on your production status and time of year. Ensure you build flexibility into the plan, and ensure all parties in the company know how to execute it.

3. Set Up a Reliable Forecasting Method: Peaks are not announced. Customers must either monitor the IESO’s daily demand forecast or rely on a third-party service to predict likely peak days. The margin for error is low because there are often more than 10 alerts each season, but only five count.

4. Prepare for Early and Frequent Peaks: Historical data shows peak days often begin in June. Waiting until July to start curtailing is usually too late. Any weekday with high temperatures, high humidity, and low wind or solar generation should be treated as a potential peak. Keep in mind that peaks can also happen in August, September, and even in January or February. Many companies miss the later ones due to curtailment fatigue. Make sure your plan accounts for different seasonal scenarios throughout the year.

5. Understand the Cost Implications: Facilities with high coincident demand during peaks carry a proportionally larger share of Class A GA costs. Even one poorly managed peak can result in increased charges for all 12 months of the next adjustment period.

Other Considerations

• Review last year’s performance. If your curtailment efforts didn’t align with actual peak hours, adjust your approach.
• Update internal communications. Make sure relevant staff know when and how to respond to peak alerts.
• Coordinate across sites. If you have multiple facilities, responses should be coordinated to avoid mixed outcomes across your GA allocations.

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