A cheap, clean nuclear-and-hydro base, but availability is tightening through the nuclear-refurbishment cycle and Bill 40 introduces managed, economic-benefit-prioritized connections for large data centers. Strong, but getting more selective.
See live grid data →Why: Bill 40 lets the Minister prioritize and approve large data-centre connections by economic benefit, so access is becoming managed and selective rather than open.
What would change the read: A clear, open large-load connection pathway rather than case-by-case selection.
For new supply: Ontario is procuring new firm supply and building transmission with First Nations equity partners; replacement capacity for the Pickering refurbishment is the near-term opening.
Beyond the grid: Indigenous consultation is central to new transmission and is increasingly structured as equity partnership rather than a late-stage veto risk: Ontario directed Hydro One to build the Red Lake Transmission Line under a model giving proximate First Nations a 50 percent equity stake, and signed a memorandum of understanding with five First Nations on the Barrie-to-Sudbury line. Hydro One Global News
Managed access: Bill 40 (2025) lets the Minister prioritize large data-center connections by economic benefit; approved projects proceed, new ones face selection.
Tightening availability: nuclear-refurbishment outages and demand growth are narrowing the practical margin.
Cheap power: low regulated wholesale, a continued advantage.
Moderate momentum: a real and growing Toronto-area market.
Clean grid (~80 g), nuclear and hydro led.
Distribution reliability (rural feeders, storm exposure) is moderate and not the binding concern here.
What this means: A large new load faces occasional exposure here. Monitor conditions and keep a contingency plan.
modelled
Large firm baseload leaving as demand climbs: Pickering Units 5-8 (about 2,000 MW) go offline in September 2026 for refurbishment into the mid-2030s, and Unit 4 was permanently retired in 2025. IESO planning shows needs emerging as data-center demand rises. Steps down if replacement firm capacity clears procurement.
What this means: A large new load should expect genuine exposure to forced power cuts (curtailment), price spikes, and delays in getting connected, and should design in backup power or firm supply contracts.
assessed · CNSC approves Pickering to end-2026 (NucNet) · Pickering-4 permanently shut (NucNet)
We have not compiled what firm service actually promises here: whether it is firm, non-firm or interruptible, the conditions under which you can be curtailed, the redundancy required of you, and the transfer time behind any N-1 commitment. Treat this as an open diligence item, not as an indication that service is firm.
Utility feeds, UPS, storage, on-site generation, islanding, black start and the residual energy you still expect to lose are properties of a specific site design, not of a market. This layer only exists once there is a site, and we never assert it for you.
What this means: The supply picture looks likely to tighten; a new load should lock firm supply early and expect competition for capacity.
High
This market's friction level, wait band and full story are free here. The precise typical wait in months, and every market ranked side by side, are the Analyst Desk.
Any load above 10 MW connecting to the IESO-controlled grid needs both an IESO System Impact Assessment and a transmitter Connection Impact Assessment, which alone can run more than 12 months, then a multi-year queue for line upgrades and new substations. Bill 40 (2025) creates a separate class for data centres and lets the province prioritise or condition their connections, so access is becoming managed rather than first-come.
Data-center share of demand pressure: Rising. Sources: Torys: connecting data centres in Ontario · Data centre regulation in Ontario (BLG). The full cross-market connection dataset is available through the Connection Friction Feed.
$55 to $100 per MWh
Midpoint about $78 per MWh
Ontario's low wholesale price is misleading on its own: the province recovers most of its generation cost through the Global Adjustment, not the spot price, so the wholesale figure alone understates the true cost by a wide margin. A large load pays wholesale plus Global Adjustment plus transmission, well above the wholesale number but below a residential all-in rate, and a large Class A load can lower the Global Adjustment by shifting demand off the top five annual system peaks.
This market's band is free here; the ranked cross-market table with every market's precise midpoint is the Analyst Desk. See the ranked view.
Basis: triangulated from public sources, in US dollars per MWh delivered to a large high-load-factor load, excluding refundable taxes. Sources: Ontario wholesale price and Global Adjustment (IESO) · Regulated Price Plan price report (OEB).
Limited
0 of 3 data layers measured
Full
3 of 3 dimensions: reliability, connection, cost
June 2026
per-layer vintages below
| Layer | Method | Vintage | Freshness | Source |
|---|---|---|---|---|
| PGIQ Rating opinion | opinion | June 2026 | Current | PGIQ methodology |
| Reliability review | assessed | 2025 | Fresh | CNSC approves Pickering to end-2026 (NucNet) |
| Connection friction | proxy | 2025/26 | Fresh | Torys: connecting data centres in Ontario |
| Realized cost | triangulated | 2026 | Fresh | Ontario wholesale price and Global Adjustment (IESO) |
Freshness reflects each layer's refresh cadence: reliability annual to three-yearly, capacity-auction and queue yearly, tariffs every year or two. The full cross-market freshness dashboard is at /data-quality.
Not compiled for this market. Identify the serving operator before relying on any figure here, because a market-level read is an average over territories.
Who runs the connection process: not yet compiled for this market. This is wayfinding rather than evidence, and its absence is a gap in our compilation, not a fact about the market.
The real-world events that test our Tier 2 call for Ontario: 1 challenges it. Each is dated and cited, so you can check the rating against what is actually happening on the ground.
The Act lets the Minister prioritize and approve large data-centre connections by economic benefit; approved projects proceed, new ones face selection.
Source: Torys ↗How Ontario's reliability-adjusted score and tier have moved, month by month. Part of your Analyst Desk.
This page is our full read on Ontario alone, and it is free. To decide where a large load should actually go, you need every market side by side, ranked on recurring cost and time-to-connect, with the history and alerts when your shortlist moves. That is the Analyst Desk.
With your Analyst Desk, compare Ontario against every market side by side, ranked on recurring cost and time-to-connect, with the full history and shortlist alerts.