​ISO-NE's 2026 Long-Term Load Forecast projects net load rising 36.8% from 117 TWh in 2026 to 160 TWh in 2046. This 43 TWh increase is the smallest absolute addition on the Eastern Interconnect, but the additions will fundamentally change New England’s system shape.

Winter peak overtakes summer in 2036 under the central-peak forecast (50/50 forecast) and in 2035 under high-peak forecast (90/10). Heat pumps (HPs) add 12.4 GW to the winter peak by 2046 while electric vehicles (EVs) add another 5.9 GW. Large loads, including data centers, add just 132 MW.

For BESS, the load forecast opens two winter opportunities: intraday volatility driven by HPs and amplified cold snaps. HPs cycle hardest in the coldest hours (generally morning) and reduce output when houses are warm. EVs concentrate charging in defined overnight windows. The combination sharpens winter days into a two-hump shape with steeper ramps into morning and evening than today's relatively flatter winter profile. A winter-peaking system makes cold snaps more stressful on the grid. Both favor short-to-medium duration batteries dispatching into winter price signals.

Key takeaways