IESO Market
Renewal Program

Ontario's IESO market changes

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Ontario is introducing a financially binding day-ahead market to replace the non-binding Day-Ahead Commitment Process (DACP). Participants will lock in prices and schedules a day in advance, with deviations settled financially in real-time. This provides greater price certainty but increases penalties for underperformance or deviations from committed schedules.

Prices will no longer be calculated on a province-wide average (HOEP). Instead, Locational Marginal Prices (LMPs) will apply at each node, reflecting the real cost of delivering electricity including congestion and losses. This exposes generators and active loads to local price volatility, while passive loads continue to settle at the Ontario Zonal Price (ONZP) with adjustments.

A Single Schedule Market (SSM)

The current two-schedule system, where dispatch and pricing are based on different calculations, will be eliminated. The SSM aligns dispatch and price signals by embedding congestion and constraints directly into market prices, removing the need for out-of-market CMSC payments.

Enhanced Real-Time Unit Commitment (ERUC)

Unit commitment decisions closer to real-time will be optimized using three-part bids: startup, no-load, and energy costs. This replaces the Real-Time Generation Cost Guarantee (RT-GCG) and allows IESO to better evaluate the total cost of committing generation to meet system needs while reducing reliance on make-whole payments.

For the first time, Ontario will allow virtual transactions to provide additional liquidity in the day-ahead market. Unlike PJM or MISO, these virtuals are limited to zonal aggregates, not individual nodes, which restricts their use in hedging nodal-specific congestion but enables financial participation in price convergence.

Ontario’s MRP does not introduce internal Financial Transmission Rights (FTRs) to hedge congestion risk between nodes. Instead, congestion rents will be redistributed to loads, leaving market participants with fewer tools to hedge locational price spreads compared to other nodal markets.

Zonal Price Forecasts

As the market evolves, we will continue to adapt our forecasts to align with the IESO transition across all 10 zones. Stay tuned for more updates!

Redesigned Dashboards

Our dashboards will have zonal LMPs, congestion signals, and price spreads — replacing legacy HOEP-based views and much more.

Show simple sine waves to indicate Price Accuracy

Bid strategy tools, Risk Tracking

We help you structure compliant bids under ERUC, including startup, no-load, and energy costs. Monitor exposure to LFDA adjustments, DAM deviations, and real-time price variance.

Scenario Analysis

Run simulations to test how price volatility, congestion, and load changes impact your positions.

Early Access to Forecast Data

The IESO data feed is now running smoothly through Arcus Platform. Our forecast data will be live in the coming months.

How will the Hourly Ontario Energy Price (HOEP) be calculated after MRP?

After the Market Renewal Program (MRP) implementation, HOEP will effectively be replaced by Locational Marginal Prices (LMPs). Arcus Power’s platform will integrate these LMPs directly into our forecasts and dashboards, providing customers with real-time and day-ahead zonal price visibility. While the Global Adjustment (GA) charge remains, Arcus ensures you have access to both market prices and actionable forecasts to manage exposure under the new pricing structure.

What is the reference node in IESO under MRP?

Under the renewed market, the reference node defaults to the Richview Transformer Station. Arcus models this nodal reference directly in its data streams and forecasts. In the event of a reference node switch by IESO, Arcus systems are configured to adjust seamlessly, keeping your nodal analysis accurate.

Are there price caps or floors in real-time under the new market?

Yes. Under MRP, settlement prices will have a floor at -$100/MWh, while offers can still go down to -$2,000/MWh. The cap remains at $2,000/MWh. Arcus incorporates these constraints into our forecast models to reflect settlement realities and help users interpret market signals amid price volatility.

How many zones are available for trading in Ontario’s virtual market?

Ontario will have nine virtual trading zones under the Market Renewal Program, even though it has ten electrical zones. The Bruce and Southwest zones are combined for virtual trading purposes. Arcus Power’s market data platform reflects this virtual zone mapping to ensure users access data aligned with IESO’s definitions.

How will Financial Transmission Rights (FTRs) settle under MRP?

Financial Transmission Rights will be settled against day-ahead congestion prices under MRP. Arcus tracks and forecasts these day-ahead congestion prices for all IESO zones, supporting customers looking to hedge congestion exposure or evaluate nodal risk strategies.

How soon will Arcus Power provide data and forecasts under MRP?

Arcus is actively rolling out MRP-related data, including DAM and RTM prices, across our platform. You can track updates via our client newsletter, platform release notes, or by contacting your Arcus account manager directly. For technical questions or integration support, reach out to support@arcuspower.com.

I’m an Arcus Power customer — how can I stay informed about IESO MRP data updates in Arcus products?

Arcus is actively rolling out MRP-related data, including DAM and RTM prices, across our platform. Contact your Arcus account manager or email support@arcuspower.com for detailed briefings, data access requests, or product demos. Our team is working closely with IESO’s timeline to keep customers aligned with each phase of the transition.

Check out our Newsletter for a more details breakdown about IESO's market changes

Ontario’s electricity market is about to go through some of the biggest changes we’ve seen in decades. With the Independent Electricity System Operator (IESO)’s Market Renewal Program launching May 1, a new day-ahead market, nodal pricing, and updated commitment rules will reshape how power is priced and managed across the province.

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Get the TL;DR copy of the Market Renewal Program

We’ve put together a detailed PDF covering everything you need to know about Ontario’s Market Renewal Program and how Arcus Power is supporting market participants.

Inside you’ll find:

✔ A clear overview of key market changes

✔ Practical insights on how it impacts you

✔ How Arcus tools and forecasts are aligned for Day One

Download the copy here

IESO Market
Renewal Program

Ontario's Electricity Market is entering a New Phase

What's changing in Ontario's Electricity Market?

Timeline for Market Renewal Transition