North America Power Spring 2026 Outlook webinars: hot topics for ISONE, PJM and ERCOT

With US electricity demand continuing to increase, grid operators face a range of challenges to deliver on their remits - from managing local power markets and interregional flows to upgrading network infrastructure and adapting to the increased use of battery storage. 

Every quarter, our North America Power Outlook webinars include an exploration of key themes for individual independent systems operators (ISOs) and regional transmission organizations (RTOs). Complete the form at the top of the page for complimentary access to the full slide decks from the ISONE, PJM and ERCOT events, or read on for an overview of the hot-button topics for each. 

Insight from ERCOT into battery storage growth, behaviour and market impact 

The Electric Reliability Council of Texas (ERCOT) has seen 124% growth in battery storage installations since 2024. At 17.3 gigawatts (GW), it currently has the most installed battery storage capacity of any US ISO, making it an ideal case study for the alignment between battery discharging, net load, and real-time pricing.  

Demand in ERCOT has remained relatively stable over the past two years, with peaks around the 60 GW mark. However, net battery storage outputs have changed significantly over the period, starting at well under 100 megawatts (MW), rising notably in Q4 2024, then seeing another large increase from late 2025 - reaching maximum discharges of nearly 300 MW. 

Looking at peak hours alone, we found that maximum storage activity only coincides with real-time pricing and maximum net load around 25% of the time. Taken individually, battery activity matched peak load around 50% of the time but maximum real-time pricing only 30% of the time (see left side of chart below). 

However, while all three elements rarely coincided completely, 70% of the time they peaked within an hour of one another. Taken individually, maximum storage activity came within an hour of either maximum net load or maximum real-time pricing almost 80% of the time. 

For the most part, then, storage outputs were responsive to either net load trends or real-time pricing. However, around 15% of the time there was no alignment at all between the three factors. Events around Winter Storm Fern, which battered the country from 23 to 27 January 2026, provide a useful example.  

In the days leading up to the storm, battery outputs matched net load peaks fairly closely. However, as the storm gathered strength, batteries showed little change in activity as net loads and real-time prices rose — apparently in anticipation of an even larger price spike. When that failed to materialise, batteries finally began discharging when net loads were dropping and prices were very low. 

For more on this and other special topics for ERCOT, including transmission upgrades and changes under its Real-time Co-optimization + Batteries (RTC+B) framework, download the full presentation deck and webinar recording by filling out the form at the top of the page. This also includes an in-depth winter 2025-26 recap and Spring 2026 outlook. 

Lessons from the first year of ISO New England’s day-ahead ancillary market 

The beginning of March marked the first anniversary of the introduction of the ISO New England’s (ISONE’s) Day-Ahead Ancillary Service Initiative (DASI), which replaced the forward reserves system. DA ancillaries will be critical for ensuring that non-intermittent generators have a lifeline to continue operating as renewables gain more market share and revenue becomes more unpredictable. 

The initiative does seem to be incentivising load to seek more day-ahead supply even as more wind capacity means greater bearish RT risk; average monthly demand clears this winter were 0.4-0.9% higher year on year. As a result, resources offering to meet daily load requirements are now gaining more revenue from the day-ahead market and reducing reliance on the out-of-market measures that played a heavy role before DASI. Net Commitment Period Compensation (or “uplift”) payments this winter fell from US$4.6 million to US$1.42 million year-on-year, indicating progress on that front.  

However, ISONE continues to struggle with publishing an accurate RT LMP forecast before each operating day, and so the ancillary strike prices still often underemphasize the risk that gens take on by offering the Energy Imbalance Reserve product. Generators are contending with the reality that high closeout costs may be higher than the revenue from Forecasted Energy Requirement (FER) prices they receive if real-time prices spike, so the pressure to be able to clear in RT during market volatility remains high. Generators should be expected to continue to hedge that risk with higher offers, and Forecast Energy Requirement (FER) prices are therefore likely to stay strong.  

Wood Mackenzie has conducted analysis of Energy Imbalance Reserve (EIR) offers between March and September 2025. Unsurprisingly, it is primarily gas and hydro plants willing and able to respond to real-time events that have been submitting offers; gas plants tended to submit offers for all hours every day, whereas hydro resources, especially pumped hydro, were selective in when they chose to offer. 

ISONE’s daily real-time LMP forecast was the driving factor for EIR offers from natural gas resources, with much less correlation seen in their RT market offers. This may imply that competition forces generators to put in minimal bids to ensure FER price revenue at the risk of facing subsequent closeout costs. Generators seem to be willing to weather the difficulty posed by RT prices frequently hitting strike prices and have been resilient in this evolving market. 

To explore this topic in more detail, fill out the form on this page to access the full presentation and webinar replay. This also includes an in-depth winter 2025-26 recap and Spring 2026 outlook for ISONE. 

A structural shift in interregional power flows between PJM and MISO 

Two of the largest markets on the Eastern Interconnection – the PJM Interconnection and the Midwestern Independent Service Operator (MISO) – have had close ties when it comes to market operations and power flows. Historically, PJM has been a net exporter of power to the latter, especially on windy days. However, W-E flows from MISO into PJM have become more common on average over the past few months, which has materilized across several different constraints that have become commonplace between the two markets, including Chicago Ave – Praxair and Stateline – Roxanna.  

These periods of exports from MISO into PJM have mainly been in response to price instability in PJM, which often leads to cascading ripple effects on MISO pricing. During a particularly volatile morning peak in PJM in early February, several GW of power were drawn from MISO, which itself was facing supply issues in the form of wind underperformance. As a result, prices spiked in both markets, with conditions stabilizing once PJM’s thermal stack ramped up in response.  

Our analysis indicates flows from MISO into PJM are set to increase year-over-year into the next decade and beyond, driven by factors on both sides of PJM’s market equation: 

Rising demand, particularly from data centers, initially centred on Mid-A and South but extending to other areas of PJM — with peak demand expected to reach 200 GW by 2040. 

Supply constraints driven by thermal retirements, particularly coal — at least until alternative capacity is installed — resulting in tighter demand margins by the early 2030s. 

Easier interregional flows: planned upgrades to MISO's transmission grid including installing high voltage lines connecting most of the Midwest will allow power to flow more easily from MISO into PJM (and potentially from SPP) 

As a result, such events are likely to become a recurring phenomenon, with instances of real-time price volatility in PJM driving imports from MISO, creating a ripple effect on prices in MISO itself. 

To dive deeper into this issue, fill out the form at the top of this page to download the full PJM presentation deck and recording, which also includes a comprehensive winter recap and spring outlook for this RTO. 

You may also want to learn more about Wood Mackenzie’s Power Trading Analytics products.