Beyond Labels

A 360° Discussion of Foreign, National and Local Policy Issues

March 1: Local Solar

There has been much publicity and debate around the deployment of large- and small-scale solar projects in the Blue Hill area. Much of the “debate” has been held in the context of public hearings and letters to the Weekly Packet—neither being a great forum for exchange of information.

On Monday, we’ll review the debate as it has been shaped to date, continue the discussion and, hopefully, begin to separate fact from fiction.

Among the specific questions to be discussed are:

  • To what degree should large-scale solar “farms” be specifically regulated on the Blue Hill Peninsula? For example,
    • Should these regulations be structured to ensure minimal safety standards and only moderate impacts on the scenic and other resources, or
    • should they be constructed in a more restrictive way that effectively discourages/prohibits large scale (say, 5+ acre) farms?
  • One of the factors that has come to light is that Versant Power can (and does) limit connectivity of solar power producers to its local substation, which has limited capacity.
    • Should this limited resource be protected to ensure that small-scale producers (like rooftop arrays) can be assured of access to net metering connections to Versant?
    • If capacity were set aside, how can we ensure that it is actually used in a timely manner?

1 Comment

  • I will again be delayed to the meeting tomorrow and want to relate a couple of things about the present solar situation.

    There was a piece in the portland paper today (Sunday) about the state of the electric grid in Maine. In short, the grid is not ready to have any significant amount of solar current fed into the existing delivery lines. Those lines feed the transformers that supply 220V power to homes. The 220v source is center-tapped so as to afford two separate 110V services available as well as 220V volt service. The delivery lines, that feed our transformers are single-phase, loaded at 11,000 (11kV).

    These 11kV lines rely on the power limits of the local substation which were never designed with the idea of two-way power in mind. Certain disruptions could cause a solar-generated power flow to run back to the substation with damaging results. While not likely to happen frequently, it does make Versant nervous. Our substation has about 5MW capacity.

    Transmission lines are three-phase and supplied at 45kV or higher. Such lines are seen on the Ellsworth road. Transmission lines would be able to handle large solar farm power input. Such farms would also need more expensive equipment in order to convert the 24V or 48V single-phase solar to 45kV, three-phase power.

    A 3MW solar farm tied to an 11kV line would load about 270 amps into the line and potentially back to the substation. The same 3MW tied to a three-phase, 45kV line would be loading only 20 amps into each line.

    Versant has said that they would love to see solar farms tied to transmission lines, such as those along the Ellsworth road.

    I hope to join the conversation after my hour in a dentist’s chair. _____Hugh

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