The region’s millions of households and businesses create the demand for electricity, which must be produced the instant it is needed because electricity can’t be effectively stored. (Learn how ISO New England runs the power grid.)
These are the days with the highest demand (electricity use) recorded in New England since the ISO began managing the power grid in 1997. The top days typically occur during the work week in summer.
This demand data comes from the Daily Summary of Hourly Data Report, available on the Zonal Information page. The daily peak load for the regional system is included in the “SYSPeak” column on the “ISONE CA” worksheet. The “DT” (date type) column represents the day of the week, where Monday is 1 and Sunday is 7.
In New England, the highest demand for electricity during the year typically occurs during the summer season.
Until 1989, New England was a winter-peaking system, and in the early 1990s, the region had nearly twin winter and summer peaks. Many factors have contributed to this dramatic change. For example:
Since 2005, total annual demand for electricity from the region’s power system has been declining. Several factors have played a role, though weather is typically the biggest determinant of electricity demand in any given year:
Energy-efficiency measures and behind-the-meter solar power have also been helping to flatten the growth in peak demand, which had previously been rising in New England. Peak demand is the highest amount of electricity used in a single hour, and the ISO must ensure that the region has sufficient power resources or imported electricity to meet it. Learn more about the forecasted effects of energy efficiency and solar power below.
The ISO forecasts that EE measures and behind-the-meter solar photovoltaic (PV) resources will continue to noticeably reduce demand for electricity from the regional high-voltage power system:
Without the demand-reducing effects of EE and PV, New England’s overall electricity use would be expected to grow an average of 0.9% annually over the next decade, from 140,583 GWh in 2017 to 152,593 GWh in 2026, while peak demand under extreme summer weather would rise at an average annual rate of 1.0%, from 31,529 MW in 2017 to 34,531 MW in 2026. These effects are illustrated in the graphs below.
See Key Stats—Resource Mix for details on the growth in EE, PV, and other clean-energy resources.