HALLOWELL, Maine (AP) Maine’s utility regulators have formally launched an investigation into Central Maine Power’s handling of solar projects.

The Maine Public Utilities Commission’s unanimous decision Tuesday follows an uproar over CMP’s warning that connecting solar projects to the grid may be more costly than expected. Gov. Janet Mills and the Maine Renewable Energy Association were among those pressing for an investigation.

CMP sent emails to the developers of solar power projects warning of additional costs because of unanticipated problems in connecting to the grid.

But the utility quickly backtracked amid strong criticism, and said it had found faster and less costly ways to get solar energy onto the grid.

The company will “fully cooperate” with the commission’s investigation, CMP spokesperson Catharine Hartnett said.

The utility has been challenged by more than 600 requests in less than two years to interconnect some 2,000 megawatts of new power onto its distribution network because of changes in state policy. That figure is 300 megawatts more than CMP’s system’s peak load now, she said, “creating significant technical challenges.”

“This is great news for achieving Maines’ climate policy objectives, but such transformational changes must be managed with careful and timely study, and proper execution to ensure the continued safe and reliable service to our customers,” she said.

The National Resources Council of Maine accused CMP of “hindering solar projects in its territory” and asked for the utility to be held accountable.

“Maine deserves a utility that is an active partner, not an obstacle, in the transition to a clean energy economy,” said NRCM staff lawyer Sue Ely.