PJM Keeps the Season Bright


Just as NORAD tracks Santa’s progress across the globe on Christmas Eve, PJM Interconnection accounts for holiday bustle to match the production of electricity with consumer demand.

To understand the season’s impact on electricity demand, PJM reflects on historical electricity usage that has powered the holiday traditions of 65 million people across 13 states. This time of year, workplaces empty out, many people stay home, and electricity demand slacks – even with billions of Christmas lights added to the mix.

As we noted last month in a story about the unique conditions on Thanksgiving, there are a few days of the year, including Christmas Day and New Year’s Day, for which PJM must independently forecast the demand for electricity. In special circumstances like these, human behavior skews typical electricity use patterns.

For the six weeks from Thanksgiving through New Year’s Day, special forecast techniques help predict the draw on the system, said PJM Senior Lead Economic Analyst John Reynolds. PJM custom-designed estimates account for the impact of holiday lights alone. Depending on what day of the week the holiday falls, PJM relies on historical forecasts to estimate dips in power usage. Since Christmas falls on a Wednesday this year, for example, PJM dialed the power forecast back slightly for Tuesday and Thursday.

Early on Christmas Day, when not a creature is stirring, load ramps up two-hours behind the typical weekday morning. In contrast, midnight power usage on New Year’s Eve burns as bright as the typical dinnertime peak. On the first day of 2020, New Year’s Day will dawn extra flat while many households sleep late.

Deck the Halls

As holiday excitement grows, PJM forecasts heightened power draw from holiday lights and other electrical decorations (Snoopy on a Zamboni inflatable, for one). Predictions account for a growing number of bulbs to shine each day, beginning on Black Friday, until the stockings are all hung with care by Dec. 23.

Nationwide, the draw from decorative holiday lights accounts for just 0.2 percent of all electricity consumption, or 6.63 billion kWh, according to the U.S. Department of Energy. The growing popularity of LED lights, which offer 80–90 percent savings on electricity compared to incandescent bulbs, should continue to reduce that impact.

According to the U.S. Department of Energy, if 100 percent of U.S. households swapped their strands of incandescent holiday lights for LEDs, about 1,000 MW of energy would be saved – about the capacity of a small nuclear power plant or large solar array.

Still, predicting electricity use from all sectors – even the twinkle of holiday lights – is part of the job in order for PJM to effectively forecast and dispatch just the right amount of power to keep the grid in balance.

Unwrap real-time grid conditions at pjm.com or on the PJM Now app.