Blocked Dispatches by the IESO Increases Again in July (Dispatch Deviation Report)
The IESO has released the Dispatch Deviation report for July, which has set a new high for market interventions since March 2022 (no reports are published prior to this date). There were 14,929 blocked and one-time dispatches for the month, averaging 1.7 IESO interventions to the dispatch algorithm every 5 minutes (noting 5-minute intervals can experience multiple interventions). Compared to July 2024, July2025 has recorded more than triple the number of blocked and one-time dispatches.
Weekly Day-Ahead and Real-Time Price Trends by Components and by Zone
Day-Ahead (DA) and Real-Time (RT) zonal prices decreased compared to the previous week. DA zonal prices ranged from $48/MWh (Niagara) to $55/MWh (Ottawa), while RT zonal prices ranged between $34/MWh (Niagara) to $48/MWh (Ottawa).The DA and RT price by zone and by component for the past week is shown below.
Day-Ahead and Real-Time Prices
Last week posted some of the lowest prices since the launch of the renewed market. The weekly average hourly day-ahead OZP was $51.50/MWh, while the real-time OZP was $37.09/MWh. There were no real-time hourly OZP spikes greater than $200/MWh, with the highest price hitting $137.54/MWh (on August 24). The peak Ontario Demand last week was 20,922 MW (on August 22, HE 17). The peak demand on August 24 – when OZP hit its highest level – was 18,610 MW at HE 18. There continues to be large price spreads between DAM OZP and RT OZP.
OR Prices
Both real-time and day-ahead Operating Reserve (OR) prices are very low relative to previous weeks and historical averages. The average weekly day-ahead 10S price was $5.52/MW, while it was lower at $0.59/MW in real-time. The most notable trend last week is the very high day-ahead 10S price spike of $70.27/MWh (coincident with one of the day-ahead OZP spikes last week).
Day-ahead OR prices closely tracked the trend in energy prices. The highest day-ahead OR price was $70.27/MWh which occurred on August 18, HE 19. For reference, the day-ahead energy price was $110.77/MWh at this time.
Real-time OR prices were low (i.e., near $0/MWh) for several hours of the week with OR prices exhibiting less volatility compared to energy prices. The highest real-time OR price was $9.38/MWh on August 24, HE 19.
Zonal Prices and Congestion
Last week, the Niagara zone saw more frequent hours of negative congestion, while both the Ottawa and East zone saw more hours of positive congestion. Similar to most other weeks since the renewed market launched, the Northwest and Northeast zones saw negative congestion in the day-ahead timeframe. Congestion in the northeast zone was very minor and the Northwest zone’s congestion was moderate with a low of -$10.81/MWh. For the Niagara zone, the most extreme negative congestion was on August19. Positive congestion was observed in Ottawa and in the East zone on August 23, HE 14 to HE 21.
Real-time zonal prices in the Northwest and Northeast remain volatile – with the Northwest seeing large swings from positive to negative congestion. There were several hours of positive congestion for the Northwest, with a large swing from positive to negative congestion hours occurring on the last hours of August 22 to the evening of August 23. The Northeast zone saw minor negative congestion mainly on August 24. The highest congestion was $55/MWh and the lowest congestion was -$30.40/MWh for the Northwest zone (also during this swing in congestion period).
Like the week prior, the Ottawa and East zone experienced positive real-time congestion. The positive congestion occurred on August 24, HE 17 to HE 19 and HE 21 and hit a high of $948.77/MWh and $302.90/MWh for the Ottawa and East zone respectively. The peak positive congestion for these zones was coincident with the peak real-time OZP observed last week. The Niagara and Southwest zones saw minor negative congestion. The Toronto zone saw minor positive congestion last week, also only in the same hours as the Ottawa and East zones.
