Frustrated by months of delays, members of Maine’s solar industry say Central Maine Power’s inability to complete interconnection studies on time is putting projects in jeopardy, and they are asking the state Public Utilities Commission to oversee the process.

The conflict involves the completion of so-called cluster studies, technical reviews conducted at the transmission system level. They are required by ISO New England, the region’s electric grid operator, whenever groups of energy projects want to connect through a common substation.

The studies include voltage, thermal and short-circuit analyses. They are done to ensure system reliability, so that adding large amounts of new, intermittent generation doesn’t have adverse effects on the stability of the electric grid.

“After frequent discussions over many months with CMP staff and independent experts, it is clear that CMP has failed to meet its obligations or make a reasonable effort to apply adequate resources that would enable these transmission/sub-transmission studies to be addressed properly and timely,” industry representatives wrote to the PUC last week.

The consequence of CMP’s inaction is that two years after lawmakers passed a landmark bill promoting solar development, the utility is still at least six months from having results for the vast majority of these cluster studies, according to the Coalition for Community Solar Access and the Maine Renewable Energy Association.

But in an interview Monday with the Portland Press Herald, a top CMP executive said the utility is working hard to complete the studies amid shifting requirements and with a limited pool of qualified experts.


“We certainly appreciate their frustrations,” said Eric Stinneford, a CMP vice president.

Stinneford noted that the scope of work required by ISO New England on these studies has become increasingly complex, as more solar projects are proposed in the six-state region. There are only so many consultants and in-house experts available to make the assessments, he said.

Despite this, CMP has pushed 145 projects through the process to date, Stinneford said, representing 500 megawatts of solar capacity. That’s enough generation to power roughly 95,000 average homes, according to industry estimates. However, another 196 projects with a total rating of 751 megawatts are awaiting completed studies. The projects are in a total of 20 cluster areas.

The PUC said Monday that it received the solar industry’s letter and will wait for it to file a formal request, as is standard protocol. The commission also noted it is already examining related issues in two separate cases.


The complaint to the PUC is just the latest squabble between solar developers and Maine’s largest electric utility.


Maine’s fast-growing solar industry was in an uproar in February, complaining that CMP was causing unexpected delays and requesting last-minute, multimillion-dollar charges to connect solar farms to the company’s substations. After Gov. Janet Mills called for an investigation, CMP said it had found some technical solutions to do the work faster and cheaper. Since then, CMP’s top management and engineers have instituted ways to slash substation upgrades from as much as $15 million to less than $375,000.

But for the solar industry, many questions remain unanswered. Last spring, the two trade groups asked the PUC to formally open an investigation, which it did on April 6. Among the issues: When did CMP learn the extent of the so-called “over-voltage” problems it faced trying to satisfy hundreds of new interconnection requests? Was the response prudent? If not, should the company face any penalties?

This investigation has been moving through the PUC process, which includes reviewing tens of thousands of emails as well as in-depth questioning of key managers by staff lawyers. Another so-called technical conference is set for Friday.

The ongoing PUC probe focuses on connections at the local distribution level, whereas the latest industry concern is with regional transmission-level studies. 


Both issues are important, however. Maine has ambitious goals to fight climate change by encouraging residents to heat homes and drive cars powered by electricity, not oil and gas. Large-scale solar projects will be critical to powering this envisioned clean energy economy, and hundreds of projects already have been proposed.


But the transformation could take many years. And if solar farms can’t hook into the power grid – for whatever reason – that’s an immediate problem.

The overall impact of delay is that some projects will lose their ability to get financing or contracts and land leases will expire, said Kaitlin Kelly O’Neill, the Northeast regional director for the solar coalition. O’Neill noted that while one cluster study has been completed in the Augusta area, several others in CMP’s service territory are being held up.

O’Neill was asked if solar developers were experiencing the same level of delay with Versant Power, which provides electric service for much of eastern and northern Maine. She said it was too soon to say, as some cluster studies were just beginning at Versant, which is a much smaller utility with fewer solar proposals.

Frustration with the CMP delays has led seven solar developers that were part of a working group meeting with the company on alternative solutions to abandon the process. In a June 16 letter to Stinneford, representatives of companies – including Longroad Development LLC, Borrego Solar Systems and BlueWave Solar – said they felt their efforts had been “exhausted,” and they requested that CMP “take immediate action” to meet cluster study timelines.

“This will result in the inability for most projects to advance to construction and will prevent a meaningful amount of clean energy from coming online in CMP territory,” they wrote about the holdup.

The developers also called for CMP shareholders to pay for any “catch-up” expenses needed to meet study timelines.

Stinneford said that’s not going to happen. Longstanding regulatory policies require generators to pay the cost of interconnections, he said, not shareholders or ratepayers.

Both CMP and the solar developers agree on one thing: The bottleneck in bringing solar online isn’t unique to Maine.

In Massachusetts, state utility regulators opened a case to review distributed generation connections in 2019, after utility National Grid put many solar projects on hold to conduct cluster studies. Last year, National Grid concluded that most of the delayed projects could move forward, without added cost.

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