New England’s Electricity Use

Across New England, millions of households and businesses rely on electricity from the grid to power lights, appliances, machines, computers and phones, and more. Demand varies second-to-second throughout each day, meaning electricity must be available the instant it’s needed.

Trends in Annual Use

Net annual energy use in New England grew steadily between 1995 and 2005, driven primarily by increased economic growth and the increased use of air conditioning.

Since 2005, net annual energy use has trended downward mainly due to an increase in energy efficiency from advanced cooling and heating technologies, energy-efficient appliances and lighting, and increasing levels of “behind-the-meter” solar (BTM PV) generation.

As shown in the chart below, though, levels of peak demand—the highest amount of electricity used in a single hour—can vary significantly from year to year. New England’s power system is planned and operated to serve demand during these peak hours, which can still see spikes even if annual use is not historically high.

Fast Stats
  • 7.5 million retail electricity customers; population 15.1 million
  • 116,719 gigawatt-hours (GWh) total annual energy served in 2024 (subject to adjustments)
  • 136,355 GWh all-time highest total annual energy served, set in 2005
  • 28,130 megawatts (MW) all-time summer peak demand, set on August 2, 2006
  • 22,818 MW all-time winter peak demand, set on January 15, 2004
  • 1.2% average annual increase in regional electricity demand forecast through 2034, factoring in forecasts for energy efficiency, behind-the-meter photovoltaics, and electrification of transportation and heating
  • 0.9% average annual increase in summer peak demand forecast and 2.9% average annual increase in winter peak demand forecast through 2034 under typical weather conditions, factoring in forecasts for energy efficiency, behind-the-meter photovoltaics, and electrification of transportation and heating

Annual Energy Use vs. Peak Demand, 2000-2024

Peak demand vs. annual energy use

* Annual energy use, also known as net energy for load (NEL), is the total amount of grid electricity produced by generators in New England and imported from other regions during the year to satisfy all residential, commercial, and industrial customer demand.

** Peak demand represents the sum of metered generation and metered net interchange, less demand from pumped storage units. Starting with full market integration of demand response on June 1, 2018, this total also includes the grossed-up demand response value.

Weather Drives Demand

New England typically reaches its highest demand for electricity during the summer, when warmer weather leads to increased use of energy-intensive air conditioning. The highest level of demand observed since the ISO began managing the power grid in 1997 was 28,130 megawatts (MW), recorded during a heat wave in August 2006.

Summer peaks on the hottest and most humid days have averaged around 25,600 MW since 2000, while peaks on the coldest days have averaged around 21,000 MW.

New England was a winter-peaking system until 1989, and in the early 1990s the region had similar winter and summer peaks. Growing use of air conditioning contributed to this dramatic change. However, as state policies drive adoption of electric space and water heating systems, New England is expected to again have a winter peaking system in the 2030s.

The region sees its lowest levels of demand in the spring and fall, with daily peaks averaging well below 20,000 MW. On mild, sunny days in these shoulder seasons, electricity produced by BTM PV installations can send demand for grid electricity plunging in a phenomenon known as the “duck curve.” Over the past several years, the ISO has observed record low levels of demand each spring. Such days are not disruptive from a grid operations perspective—the ISO’s sophisticated modeling and forecasting methods allow system operators to anticipate and prepare for these conditions.

Top Demand Days

All Days Winter Days
DATE DEMAND (MW) DATE DEMAND (MW)
August 2, 2006 28,130 January 15, 2004 22,818
July 22, 2011 27,707 December 20, 2004 22,631
August 1, 2006 27,467 January 14, 2004 22,477
July 19, 2013 27,379 January 18, 2005 22,141
July 18, 2006 27,329 January 16, 2004 21,931

Impact of Energy Efficiency and Solar Power on Grid Electricity Use

Today, about 25% of total system capacity is provided by distributed energy resources that reduce demand from the grid.

State policies and wholesale market revenues support energy efficiency (EE) and demand response programs. New England states have invested billions of dollars in EE programs that promote the use of energy-efficient appliances and lighting and advanced cooling and heating technologies, with another $11 billion expected through 2033. Nearly 3,600 MW of demand capacity resources (including demand response, energy efficiency measures, and distributed generation) reduce electricity demand from New England’s power grid—that’s more than 11% of system capacity acquired in the most recent Forward Capacity Auction. And New England is first in the nation to innovate and enable demand resources to fully participate in the energy and reserve markets.

Providing incentives for local/residential solar power is also a top priority for New England policymakers, with the states spending billions of dollars on making solar energy affordable for consumers. In 2010, New England had about 40 MW of behind-the-meter solar photovoltaic (BTM PV) resources. Today, the region's BTM PV installations have a combined nameplate generating capability of about 5,000 MW. The region is on track to exceed 8,000 MW over the next decade. Though these resources don’t participate in the markets, the markets are flexible to changes in grid demand, so grid electricity is not over-produced—or over-purchased.

ISO New England’s 10-Year Electricity Demand Forecast

The ISO forecasts that electrification of transportation and heating will drive increases in both energy use and peak demand in New England over the next 10 years. The ISO develops gross long-term forecasts for annual and peak electricity demand using state and regional economic forecasts, years of weather history in New England, and electrification forecasts. Results of the ISO’s forecast for  behind-the-meter solar photovoltaic (BTM PV) is applied to the gross forecasts to develop net long-term forecasts. Since BTM PV reduces the amount of electricity consumers draw from the bulk power system, the net forecasts represent actual grid demand.

  • Net electricity use is expected to increase, by an average of 1.8% annually, from 117,262 GWh in 2025 to 130,665 GWh in 2034.
    • BTM PV is projected to reduce grid demand by 5,555 GWh in 2025, rising to 11,487 GWh in 2034.
    • Electric vehicles (EVs) are expected to account for 8,735 GWh of grid demand in 2034, while heating electrification is expected to account for 8,049 GWh that year.
  • Peak demand under typical summer peak weather conditions is expected to rise annually at a rate of 0.9% over the 10-year period, increasing from 24,803 MW in 2025 to 26,897 MW in 2034.
    • The net forecast includes an average peak demand reduction of 1,870 MW each year as a result of BTM PV.
  • Peak demand under above-average summer peak weather is expected to rise from 25,886  MW in 2025 to 28,297 MW in 2034.
    • Transportation electrification from EVs is forecast to contribute 852 MW to above-average summer peak demand in 2034.
  • Winter peak demand is forecast to increase an average of 2.9% annually under normal conditions. For normal winter peak weather, net peak demand is expected to increase from 20,056 MW in 2025/2026 to 26,020 MW in 2034/2035; for below-average winter peak weather, the net peak is forecasted to increase from 21,125 MW to 28,714 MW in over the next decade.
    • Transportation electrification is forecast to contribute 1,764 MW to the winter peak under typical conditions in 2034/2035.
    • Heating electrification is forecast to contribute 4,765 MW to the winter peak under average weather in 2034/2035.

Learn More

  • The ISO’s Forecast Report of Capacity, Energy, Loads, and Transmission (CELT) provides a 10-year snapshot of the New England power system and is used in power system planning and reliability studies. The CELT is developed each year using state and regional economic forecasts, 40 years of weather history in New England, and other factors.
  • The CELT also incorporates results from the ISO’s solar photovoltaic (PV) forecast, which project the load-reducing effects of PV resources connected to local distribution systems.
  • See Key Stats—Resource Mix for details on the growth in PV and other clean energy resources.