ISO New England forecasts about 3.5 GW solar output decline during April solar eclipse

ISO New England forecasts a 365 MW reduction in utility-scale solar power output during the April 8 US solar eclipse maximum and a 3,186 MW reduction in behind-the-meter solar power output during the maximum phase of the eclipse. The grid operator also said it is currently tracking a total of 41,582 MW of power generation projects in its interconnection queue.

On April 8, a total solar eclipse will cross North America, passing over Mexico, the US and Canada.

In New England, totality will begin in Burlington, Vermont, at 3:26 pm and end at 3:29 pm, and the partial eclipse will take place from 2:14 pm until 4:37 pm. The timing will be similar in Lancaster, New Hampshire, and Caribou, Maine, according to an ISO-NE presentation given during a March 7 New England Power Pool Participants Committee meeting.

Regarding utility-scale solar power production, after decreasing by 365 MW during totality, in the hour after totality ends utility-scale output will gain 230 MW, ISO-NE said. Similarly, behind-the-meter solar output will gain 2,260 MW in the hour after totality ends. Output will drop by 3,186 MW during totality.

As of the end of 2022, ISO New England estimates that the region had just over 6,000 MW in nameplate capacity of all types of solar PV. Solar power is becoming a larger component of ISO-NE's power generation fuel mix and thus is having a greater impact on power system operations.

For example, in 2023, there were 73 days during which power grid demand was lower during the day than it was at night. That number is up from 45 days in 2022, and before that, the phenomenon occurred 34 times dating back to April 21, 2018, the first time the grid operator observed it, according to a Feb. 28 statement.

Power generation additions

Five power generation projects totaling 562 MW were added to the interconnection queue since the last update a month ago, including one solar power project and four battery storage projects with in-service dates between 2026 and 2028, ISO-NE said in the presentation. The interconnection queue data was reported as of March 1.

In total, 404 power generation projects are currently being tracked by the grid operator, totaling approximately 41,582 MW.

Batteries and wind power account for the largest share of the incremental power generation projects out to 2030. The wind power data includes offshore wind projects that are scheduled to come online in that timeframe.

Going out to 2030, there are 17,770 MW of battery storage projects in the interconnection queue and 15,171 MW of wind power projects, accounting for 45.4% and 38.7% of the total, respectively, ISO-NE said.

By state, Massachusetts adds 21,139 MW of generation capacity by 2030, Connecticut adds 8,913 MW and Maine adds 6,071 MW. Vermont, Rhode Island, and New Hampshire account for the remainder.

However, not all projects in the interconnection queue get built. The ISO estimates that there are 20 projects totaling 1,379 MW of capacity with a high probability of going into service within the next 12 months.

That total consists of 48 MW of baseload capacity, 405 MW of peaking capacity and 926 MW of wind turbine capacity, according to the presentation.