THE WOODLANDS, Texas — MISO expects its in-service solar capacity to grow to 12 GW by the end of winter, a 50% increase over its existing fleet.
Speaking during a meeting of the MISO Board of Directors’ Markets Committee on Dec. 10, Executive Director of Market Operations JT Smith said MISO anticipates developers will finish about 4 GW of new solar generation before March hits. “That’s three times more than what we had last winter,” Smith said.
The RTO’s latest solar peak of 8 GW occurred Oct. 16.
Smith said MISO’s solar fleet even now is significant enough that the grid operator notices diurnal output patterns, with a steeper ramp requirement in the evenings.
He said members in the footprint are set to add additional 4 to 7 GW of solar generation by the end of 2025 as renewable developers bring some of their approved solar farms online.
“Next winter, we might be talking about 20 GW of solar,” Smith said.
Carrie Milton, of MISO’s Independent Market Monitor, told board members that over the upcoming winter, the RTO could experience ramping needs as high as 12 GW during the period of 3-7 p.m. She said MISO must work diligently to manage more “extreme” ramping needs.
Milton said over two instances in the fall, MISO experienced shortage intervals where prices spiked to the $3,500/MWh value of lost load (VOLL). She said in one case, generation was powering down faster than load was dropping in the evening and in another, renewable energy output fell faster than forecasted.
Milton told MISO and its board that “improved ramp management will be key,” especially as the RTO filed to increase its VOLL to a $10,000/MWh cap. “That’s going to be much more impactful,” Milton said of the higher rates.
Monitor David Patton advised MISO to expect an influx of battery storage to enter its interconnection queue soon. “Batteries are going to be increasingly economic in this environment,” he said.
MISO leadership reiterated to its board that though winter on the whole shouldn’t cause strife in the operations room, it’s preparing for at least a few challenging days.
MISO is entering winter with a 131-GW planning reserve margin requirement but a 100-GW probable demand and a 107-GW high-demand scenario. (See MISO Says Comfortable Wintertime Margins Likely in Store.) The RTO isn’t issuing serious warnings over the upcoming cold weather but isn’t ruling out a widespread freeze or snowstorm.
“We can have a mild winter — and we have the past three to five years — but you can have those days, three sigma, four sigma days that can cause tremendous damage,” MISO CEO John Bear warned.
“Each year, it’s almost predictable that something is going to happen,” Milton agreed. But Milton said even in the IMM’s analysis of worst-case winter conditions, MISO still should experience a 2% margin.
Smith noted that MISO’s past few winter storms with precarious operations have occurred over long holiday weekends. The February 2021 winter storm occurred over Washington’s Birthday, and the December 2022 winter storm occurred over Christmas.
Smith joked that he hoped MISO’s next bout of serious winter weather shows up “Tuesday on a non-holiday weekend” so members can contract adequate natural gas ahead of time.
Otherwise, MISO exited a “wholly unremarkable” fall, Smith said, with a 106-GW peak occurring Sept. 19 and short of its projected 108-GW peak.
Milton noted that over the fall, congestion costs were dramatically lower in the northwest portion of the footprint as drought conditions in Manitoba eased and MISO began receiving power exports again instead of importing to the province. She also said that SPP further improved MISO’s congestion position by implementing a remedial action scheme for the Charlie Creek flowgate in North Dakota. Milton said the scheme, which involves SPP cutting load in their footprint to avoid exacerbating congestion, reduced costs of the constraint by 95%.
The Charlie Creek flowgate has been a contentious issue between MISO and SPP since 2023, when a cryptomining facility began operations in an SPP load pocket and exacerbated congestion. (See MISO Argues to FERC for 2nd Look at Crypto-stressed Flowgate Management.)
