An arbitrator’s decision has raised doubts about the future of a proposed wind turbine in Milton and increased interest in the school system’s solar energy project.

In a final decision released late last month, arbitrator Gordon L. Doerfer allowed the town to build the turbine, but he said from April 1 to Nov. 15 it must restrict its operation to nighttime hours. During that time, the turbine would have to shut down between 7:30 a.m. and about sunset.