Just when they need air conditioning the most, Eversource customers are getting hit with a huge price hike - with some people's July bill doubled.

Bonni Shea, of Norwalk, says she was shocked by her July electric bill.

"My electric bill went up almost $100 from last month," she says.

The increase comes from higher "delivery charges," a catch-all for all sorts of fees that keep Eversource in business.

Part of the rate hike is due to higher electric transmission costs and federal mandates. But an Eversource spokesperson says much of it was forced on them — by the state of Connecticut.

"We were opposed to this. We were against this," says Eversource spokesperson Tricia Modifica.

As part of a deal to keep the Millstone Nuclear Plant from closing early and taking one-third of the state's electric supply with it, the utilities agreed to pay more for Millstone's power.

Starting July 1, Eversource says it's paying $124 million more over the next six months.

United Illuminating customers are seeing a much lighter impact. The average customer is paying just under $3 extra.

"We were... advocating for our customers against that because we knew what the price; the increase in cost was going to be for our customers," says Modifica.

Gov. Ned Lamont's administration negotiated the Millstone deal. He says the alternative would have cost customers even more.

“That would have left us forced to buy peak power, probably polluting peak power, out there in the open market, at considerable cost,” says Lamont.

"I'd ask him to take into consideration the hardship that so many Connecticut state residents are going through, and try to work out a deal to help everybody out," says Shea.

Top legislative leaders are calling for hearings on this sudden price spike.

The Millstone Nuclear Plant says it's being unfairly blamed.

A spokesperson says, "Millstone’s contract price is a great deal for Connecticut consumers. The power is being sold at a flat rate of 4.999 cents/kWh, the lowest price for a carbon-free resource in Connecticut published to date and 32% lower than the lowest standard offer price ever from Eversource, which is roughly 7 cents/kWh. The contract is for 10 years so that ensures consumers lock in low-price, zero-carbon electricity for a long time. This contract went into effect in October 2019, nine months before Eversource’s latest rate increases. It was vetted and approved by all state energy regulators. The nonbypassable federally mandated congestion cost (NBFMCC) charge recovers costs for 23 different services and programs approved by state and federal regulators. The state’s contract with Millstone is just one of these items.”