Mainers and New Englanders at large were cranking air-conditioning units and fans Tuesday to try to sweat out the record heat that swept through the Northeast.

The result of all that power usage? The highest amount of electricity the region has utilized at peak hours since 2013, as well as a low-level emergency that let operators activate reserve resources.

Maine saw temperatures in the high 90s, with humidity driving the heat index well into the 100s. Numerous cities and towns hit triple digits, either breaking, equaling or coming within shouting distance of heat records.

That included Portland, which hit 99 degrees, and Fryeburg, which hit 100 according to the National Weather Service office in Gray — both records for June 24. Augusta also reached a 100-degree high, while the Lewiston-Auburn area came just shy at 99 degrees, the weather service said.

As the heat baked down, the New England power grid also made a push for the record books. The regional grid’s usage peaked at roughly 26,000 megawatts of power Tuesday evening, according to ISO New England, which oversees the region’s power grid and serves 7.5 million retail electricity customers.

Usage peaked just shy of the region’s record, which clocked in at roughly 28,100 MW during a heat wave in August 2006.

Some experts said Wednesday that New England would have come even closer to that record — or broken it — if it weren’t for solar power.

ACTIVATING RESERVES

A low-level emergency known as Power Caution was issued by ISO New England at about 5:20 p.m. Tuesday, ahead of the expected peak usage between 6-7 p.m. That’s when the power grid routinely experiences peak usage, as people come home from work and start running appliances, according to Mary Cate Colapietro, an ISO New England spokesperson.

“A Power Caution is issued when the available capacity is not enough to meet both the expected demand and the required operating reserves,” Colapietro said. “Issuing this alert allows system operators to take additional steps, like using the reserve resources to maintain reliability.”

The Power Caution was put in place after an “unexpected loss of generation left the region short of the resources needed to meet both consumer demand and required operation reserves,” ISO New England stated in its alert. In a phone call Wednesday, Colapietro said ISO New England can’t disclose what power source failed for safety reasons.

ISO New England typically maintains between 1,560 MW and 2,250 MW of reserves that can come online within 10 minutes of activation. An additional 625 MW of reserves can be in use within 30 minutes.

For power plants in the region, “it was all hands on deck” Tuesday, said Dan Dolan, president of the New England Power Generation Association, whose members make up about 95% of New England’s generating capacity.

“Everybody who can operate was operating,” Dolan said in a phone call Wednesday. “Fortunately, I think the system worked very well. We saw remarkable performance while the system was extraordinarily tight.”

The Power Caution was eventually dropped at 9 p.m. Tuesday, but a precautionary alert was kept in place Wednesday.

SOLAR EASES DEMAND

Both Dolan and Dan Burgess, director of the Maine Governor’s Energy Office, believe solar power played a crucial role in keeping the power grid online amid such extreme demand.

“(Tuesday) evening was the highest level we’ve seen since 2013, and I think it probably would have been even higher if not for behind-the-meter solar,” Burgess said.

Solar panels, like ones found on the roofs of homes, don’t count toward the energy generated by the grid and effectively decrease the demand for the grid’s services. If it weren’t for solar panels taking the edge off, Dolan thinks the region would have broken the record set in 2006.

“Having solar power as part of the system, particularly during those really hot afternoon hours, is huge,” Dolan said.

According to Burgess, Maine has roughly 1.6 gigawatts of solar installed, and 5-6 gigawatts are generated by solar sources across New England during afternoon hours.

But reserve “peaker plants” were also needed Tuesday, some of which utilize nonrenewable sources. Burgess referenced an oil-fired plant on Cousins Island in Yarmouth and a coal plant in New Hampshire that fall under that title.

As Maine and New England ramp up development and use more sustainable energy sources, the need for fossil fuels in these instances will be reduced.

“Whether it’s transmission upgrades or onshore wind, or things like energy storage and efficiency, (Tuesday) was a good example of why those policies and actions are important,” Burgess said.