Given it has been a full year since the launch of MRP, Power Advisory will be hosting a webinar this week reviewing the price related outcomes in the renewed market over the first year. We have sent out an invite for the webinar on Wednesday, June 10th, 2026 from 11 AM to 12 PM EST.
Day-Ahead and Real-Time Price Trends by Components and by Zone
Ontario’s wholesale market saw higher prices across all zones in real-time compared to day-ahead, with the exception of the Northeast and Northwest zones that experienced some of the lowest prices since the launch of the renewed market. In particular, the two northern zones saw the emergence of extreme negative pricing. Prices in the Ottawa zone here higher compared to the other zones. DA zonal prices ranged from $13/MWh (Northwest) to $43/MWh (Ottawa), while Real-Time (RT) zonal prices ranged between -$0.34/MWh (Northwest) to $55/MWh (Ottawa). The low prices in the Northern zones were likely due to the high hydro output last month, moderate demand and long-standing transmission constraints. Hydro output was the highest since the launch of the renewed market with a total output of 4 TWh for the month. Last year May, the total hydro output was 3.8 TWh.
The DA and RT price by zone and by component for the past month is shown below. Prices in the Northwest zone and Ottawa zone were impacted the most due to high hydro output and congestion respectively.
Day-Ahead and Real-Time Prices
Compared to April, May had more frequent prices greater than $200/MWh prices, but monthly average prices were slightly lower. Compared to May of last year, last month had slightly more frequent prices greater than $200/MWh and higher monthly DA and RT OZP monthly averages. This year’s May, there were 20 real-time hourly OZP spikes greater than $200/MWh. The average hourly day-ahead OZP was $33.49/MWh in May, while the real-time OZP was $39.39/MWh. Last year’s May, there were 16 real-time hourly OZP spikes greater than $200/MWh. The average hourly day-ahead OZP was $22.49/MWh in May, while the real-time OZP was $27.91/MWh. Last month, the highest real-time OZP was $505.90/MWh (on May 18, HE 20). The peak Ontario demand was 20,820 MW (on May 19, HE 17). The May Ontario peak demand was 2,359 MW higher than the peak in April – with increased temperatures last month. The May Ontario peak demand was also 2,667 MW higher than the peak in last year’s May. The Ontario demand on May 18, HE 20 – when OZP hit its highest level – was 18,668 MW, which is well below the peak demand of more than 24,000 MW in the summer of 2025.
OR Prices
There were more real-time Operating Reserve (OR) price spikes in May compared to April. In contrast to April, May observed much higher day-ahead and real-time average monthly OR prices. However, in May of last year, day-ahead OR prices were similar but real-time OR prices were much higher. The average monthly day-ahead 10S price was $30.07/MW, while it was $17.59/MW in real-time. In May of last year, the average monthly day-ahead 10S price was $29.40/MW, while it was $40.44/MW in real-time. The highest real-time OR price spike last month was $485.27/MW and occurred at the same hour as the highest real-time OZP spike. In the day-ahead market, the most common 10S price was $0.10/MWh (occurred 5% of the time) while in the real-time market, it was $4.99/MW (occurred 13% of the time).
The highest day-ahead OR price was $230.23/MW, which occurred on May 22, HE 7. The day-ahead energy price was $42.07/MW at this time. The day-ahead OR price exceeded the day-ahead energy price in 276 hours or 37% of total hours in May. This trend is double the amount in April, where 138 hours (19% of total hours) experienced the OR price exceeding the energy price – meaning that in these hours the OR market was tight and reserve prices can put upward pressure on energy prices due to co-optimization. This trend is less than May of last year, where 322 hours (43% of total hours) experienced the OR price exceeding the energy price.
Real-time OR prices were low (i.e., near $0.10/MW) for many hours. There were several hours with real-time OR price spikes, coincident with real time OZP spikes. The highest real-time OR price was $485.27/MW on May 18, HE 20. The real-time OR prices exceeded the real-time energy prices across 82 hours or 11% of total hours in May. This is higher compared to April where 50 hours (7% of total hours) OR prices exceeded the energy prices. This is significantly lower compared to May of last year where 460 hours (62% of total hours) OR prices exceeded the energy prices.
Zonal Prices and Congestion
The average real-time nodal price (LMP) across Ontario for May is shown in the figure below. In contrast to April, nodes in Ontario showed a greater range in average LMPs. The nodes in the northern zone tended to be slightly lower than all other zones. The LMPs in Ottawa were higher than other zones due to increased exports to Quebec and more frequent FIO outages. LMPs in the Southwest zones were also slightly higher than in April.
In May, compared to April, there were several more nodes in the Northern zones with a low LMP of - $100/MWh.
In May, there was moderate congestion across a few zones in the day-ahead market. The Northwest zone saw the most hours of congestion with a low of - $125.92/MWh. The Northeast zone observed mainly negative congestion with a low of - $41.77/MWh. Congestion in the East and Ottawa zones occurred mostly at the same hours at the end of the month. The East and Ottawa zone saw a high of $21.82/MWh and high of $73.09/MWh respectively. The West zone saw minor hours of congestion with a high of $7.72/MWh and a low of -$24.40/MWh. Note that negative congestion typically means there was a constraint exporting energy from a particular zone (and lower energy prices), while positive congestion is the opposite.
In real-time, the Northeast and Northwest zone saw several hours of consecutive negative congestion throughout the month. The Northwest zone saw a high of $132.16/MWh (on May 19, HE 3) and a low of - $436.09/MWh (on May 29, HE 19). The Northeast zone saw a high of $3.80/MWh (on May 25, HE 20) and a low of - $440.07/MWh (on May 29, HE 19). The lowest congestion observed in both the Northeast and Northwest zone in May was at the same hour (on May 29, HE 19).In most of May, there were several outages (at least 150 MW not available) on the East-West Transfer East (EWTE)/East-West Transfer West (EWTW) interfaces, which can limit flows between the Northwest and the rest of the province and cause congestion. There is some reduced capacity on Flow-South (FS) (FS is operating at minimum capacity) for May. There were also several outages on the Ontario-New York Import/Export interfaces in the second half of May and on the Queenston Flow-West (QFW) in the last week of May. Note that congestion in the Niagara zone was not impacted by reduced capacity on the New York and the QFW last month (there was no congestion). There were also outages on the Flow Into Ottawa (FIO) throughout the month.
Other than the Northern zones, in real time, there was high congestion in the Ottawa zone at the same time as the East one. The Ottawa zone observed several spikes above a $100/MWh. The high in the Ottawa zone was $962.52/MWh and the high in the East zone was $428.36/MWh. Congestion also appeared in the West zone for some hours – occurring at the same time as the high congestion in the Ottawa zone. A low of -$476.80/MWh was observed. The Essa zone had minor congestion with a high of $25.33/MWh occurring at the same hour as the highest congestion observed for the Ottawa and East zones.
In May of this year, the Northern zones saw the greatest number of congested hours since the launch of the renewed market. The Ottawa zone also saw the greatest number of congested hours last month. Note that the number of congested hours in the Southwest has significantly increased but is minor in magnitude (less than $4/MWh). Congestion across all zones has increased from April to May. Compared to May of last year, congestion in the Northwest and West zones are similar. Congestion in the Northeast, Ottawa, and Southwest zones are higher while congestion in the Niagara zone is lower (close to no congestion last month). Note that the congestion observed in the Ottawa zone was also connected to outages or reduced capacity on major Ottawa-connected interfaces in the last half of the month.
As shown in the figure below, May – similar to April – saw some northern major interfaces with reduced capacity, specifically the EWTE/EWTW and FS. In contrast to April, in May, the FIO had slightly more frequent occurrences of reduced capacity and the ON-QC Beauharnois interface had no occurrences of reduced capacity.
