They spent $24,000 on solar panels. Then Eversource took four months to turn them on.

Matt and Annie Kelly took the plunge into renewable energy by spending about $24,000 for solar panels on the roof of their Cambridge home. But then it took four months for Eversource to make the routine inspection needed to flip the switch.Jonathan Wiggs/Globe Staff

Last year, Matt and Annie Kelly took the plunge into renewable energy by spending about $24,000 to install solar panels on the roof of their Cambridge home.

Once they committed to it, they wanted to move fast. The sooner they got their new system up and running, the sooner they could begin recouping their upfront cost.

The contractor they hired to handle the project told them they could expect their monthly electricity bill to plummet by about $100, to about $25. (They also received thousands of dollars in federal tax credits.)

“We wanted to save money and increase the value of our house,” said Matt Kelly, 50, a self-employed editor of a newsletter on corporate governance.

The Kellys also wanted to do their part to combat climate change. They have two small children and worry about what kind of world they will inherit. (The Kellys also recently switched to an electric vehicle.)

At first, Matt Kelly said he was wary that supply chain backlogs might cause delays. But the dozen panels arrived on time and were installed on Nov. 24. A couple weeks later, a municipal inspector signed off on the construction.

As of the middle of December, all that remained before the Kellys could “flip the switch” to turn on solar power was for Eversource to come out for an inspection and sign off.

But before the Kellys could get Eversource to do the inspection, they needed the utility to approve what it calls its “application for interconnection,” a bit of paperwork that would prove to be a huge drag on the process.

The application had been filed by the Kellys in October, six weeks before the panels were installed. For months, Matt Kelly and his contractor, Great Sky Solar of Arlington, had pestered Eversource for the status of the application but got little response.

In December, Eversource revealed that the interconnection applications filed by the Kellys and other customers had been delayed by “an IT-related issue” at the utility and apologized.

Another month passed. Requests for updates continued. “Can we please get an update on this project? It’s tremendously behind,” a Great Sky Solar project manager wrote to Eversource in January.

The Cambridge couple spent $24,000 for the solar panels atop their home. Jonathan Wiggs/Globe Staff

Finally, on Jan. 25, Eversource approved the application. But it then took almost two more weeks for Eversource to send a technician out for an inspection. By then, four months had passed since the Kellys filed their application.

The Eversource technician discovered that one of the meters had been improperly wired. Great Sky Solar immediately acknowledged its mistake, fixed it within 24 hours, and implored Eversource to return promptly for a new inspection.

But instead there was more delay.

By March 20, Matt Kelly felt abandoned.

In his e-mail to me, he wrote: “The final step is for an Eversource technician simply to come to my townhouse and activate the new meter — and Eversource is just dragging its feet on that, for months on end.

“I’ve asked Eversource directly to schedule an appointment, with no reply. [Great Sky Solar] checks with Eversource weekly, and gets no clear answer. We have asked, we have escalated, we have begged. Eversource simply takes no action. This has been going on since the first week of December.”

“It’s a ridiculous situation that undercuts Massachusetts residents trying to fight climate change, reduce our dependence on oil, or just invest in the value of your house.”

Well put, Matt.

Last week, I contacted Eversource, New England’s largest utility. Eversource promised to look into it. Two days later, I got a call from a Great Sky Solar project manager who sounded almost giddy about an e-mail he had just received from Eversource.

Here’s what the Eversource e-mail said: “Your system … has been given permission to operate and you may now be interconnected with Eversource Energy.”

A short time later, Matt Kelly flipped the switch. He felt an immediate sense of relief.

A spokesman for Eversource said the utility “definitely understands how frustrating the whole experience” was for the Kellys but said their experience was unique — “an outlier” among the more than 7,000 homes it approved for interconnection last year.

“Mr. Kelly’s project is out of the ordinary as we encountered some unique circumstances, including winter storms and an IT issue that delayed his approval,” the spokesman said.

I asked if my involvement prompted the utility to act more promptly, but the Eversource spokesman didn’t reply directly, saying “whenever there’s an issue customers should reach out to us directly.”

But that’s exactly what the Kellys had done — endlessly.

“We don’t want to see any unhappy customers out there,” he said. “And managers are reviewing the [Kelly case] to see what improvements can be made.”

I also asked the Eversource spokesman whether customers converting to solar power lowers Eversource’s profits.

“No, it doesn’t affect our bottom line and there are no intentional slowdowns in the process,” he said. “We appreciate our customers who are moving to sustainable energy. We take it very seriously.”

Eversource needs to do a lot better. Utilities like Eversource and National Grid should make the process for “flipping the switch” quick and easy for anyone willing to generate renewable energy with rooftop solar panels.

Kelly said some of his neighbors near Inman Square have watched the process he has followed to “go solar.”

“I’m recommending it,” he said. “But the process has to be much smoother, much faster.”