Tomorrow, millions of people in the US will skip their Thursday workaday routines in favor of lounging at home, watching TV, and, above all else, eating. People eat every day, of course, but Thanksgiving also means cooking, and cooking at home, and even more specifically, roasting something very large, at high heat, in an oven, for hours. That energy, or more specifically, that electricity, comes mainly from the grid. 

Thanksgiving’s unusual activity means more than just a break in the usual electricity consumption pattern. It is sufficiently unusual that we can see it in a utility or even system-wide load profile. And, there is no better example than New England, the site of the first Thanksgiving, and its grid operator, ISO New England. 

Here is ISO-NE’s load profile from the week of Thanksgiving last year. Monday, Tuesday, and Wednesday show a similar pattern: rising demand in the morning, a midday dip, and then another evening peak, followed by a swift, fairly smooth retreat to a late evening low.

Thanksgiving, though, is different. First, the load ramps quickly and are higher than during the work week. Second, it retreats rapidly, without an evening peak, presumably because most of New England was catatonic from a surfeit of turkey and disinclined to do anything. Roasting a turkey for four hours requires about 8-10 kilowatt-hours of power, which, when multiplied by millions of households, means…a lot of kilowatt-hours.  

(This pattern is not just known, by the way; it is so well known that ISO-NE regularly publishes explainers about its Thanksgiving load curve.)

As an aside, in addition to this cooking peak, utility operators also know of something called “hosting” load, when more electricity is used in a house filled with guests. But that specific effect will be counteracted by other houses being empty, and much more efficient LED home illumination will mitigate the energy impact of more lumens in a full house. 

(And as an aside-aside, LEDs have also reduced what used to be a noticeable “holiday light”, or if you will, Griswold effect. However inspiring the movie display may have been, utility executives properly note that a typical house in 1989 could only handle 100 amps and therefore a maximum of 3,000 incandescent bulbs, not 25,000.) 

But back to Thanksgiving, where the day after the holiday is also different from the workweek. There is no fast-ramping demand in the morning, and the midday shoulder load is much lower than during the week, again perhaps due to an over-abundance of turkey rendering New Englanders inactive.  

Let’s look at the holiday another way, with Thanksgiving and its neighbors overlaid on the same 24-hour X-axis. Here, the difference between days is even more apparent. Thanksgiving looks like a counter-programming to Wednesday the 27th’s workday load profile, and it seems quite different from Friday the 29th’s sessile, sleeping-off-the-turkey pattern too.

But - there’s a wrinkle here which our New England readers have probably already recognized. The region doesn’t always have the greatest weather in late November, and last year’s Thanksgiving weather was gross: a “dynamic mid-latitude cyclone” dropped rain and snow all over the six states of New England. 

That weather pattern highlights an important aspect of the contemporary load paradigm, even in a cold, often gray, northern-latitude grid: the distinction between gross load and net load, including behind-the-meter solar. 

Fifteen years ago, New England had all of 80 megawatts of installed solar; today, there is more than 7 gigawatts in the six states of ISO-NE. That much installed solar means that day-to-day changes in solar generation could be evident when we stack up a series of daily load curves. In other words, even wintry New England can have a “duck” curve…or would that be “turkey” curve? The ISO actually wrote about this effect (on Thanksgiving, no less!) back in 2018, and last year, solar was evident again in a different way.

Solar’s presence on the 27th and 29th of November 2024 meant that the effective total load was decently higher than what the region’s thermal generators could meet. It also means that the day-after-Thanksgiving lie-in was not quite so inactive. And solar’s near-total absence on Thanksgiving itself gives us a glimpse of the grid in a prior age, one where thermal generation had a near-exclusive role in meeting regional electricity demand. Last year in New England, that role was demanding, and ISO-NE did well. 

So, when you’re popping something in the oven tomorrow morning and spending hours preparing food using the gift of reliable electricity, add in some thanks to your local utility, your independent system operator or regional transmission operator, your area reliability corporation, or even your entire Eastern or Western interconnect for keeping the lights and the ovens on. 

Happy Thanksgiving from us at Halcyon to all of you!

Subscribe for more content like this; reach out with questions: sayhi@halcyon.io; follow us on LinkedIn and Twitter