Metered electricity demand in the New York ISO falls midday because of small-scale solar

New York's electric grid is running differently than it used to, thanks to rooftop and other small solar systems under 1 megawatt. These systems aren't tracked by utilities the way big power plants are, but their growing output is clearly reshaping demand patterns, especially in early spring, when sunny days coincide with relatively low overall electricity use.

Since 2018, New York has added 5.6 gigawatts of solar capacity, and about half of that is small-scale, the rooftop kind. As more of it comes online, midday demand on the utility grid has dropped, because homes and businesses are drawing more power from their own panels instead of the grid. But the effect reverses later in the day. Back in 2018, electricity demand rose by about 850 megawatts on average between 8 and 11 a.m., as people started their day. By 2026, demand in that window actually fell by about 923 megawatts, since solar output ramps up fast in the morning. Then in the evening, as the sun goes down and home solar production drops off, grid demand jumps sharply, rising by about 2,221 megawatts between 4 and 7 p.m., far more than the 681-megawatt increase seen in 2018.

For homeowners, this shows how much rooftop solar is changing the shape of daily electricity use across the state, smoothing demand at midday while making evenings busier for the grid. It's a reminder that when your own solar panels stop producing at sunset, the rest of the system has to work harder to pick up the slack.