Massachusetts Net Metering Projects Face Suboptimal Interconnection Designs
Massachusetts’ net metering program went into full effect in February, but the Massachusetts Department of Public Utilities (DPU) may have inadvertently stymied the program’s growth by issuing an order that prohibits or impedes optimal interconnection of larger projects. The Massachusetts DPU is now considering reversing course.
Under the Massachusetts’ net metering program, local utilities provide billing credit to customers with interconnected renewable energy projects that feed power into the grid. The customer that hosts the project can either use the credit against its own account or assign the credit to another account with the same utility. The amount of interconnected and net metered generation permitted under the program is subject to two separate caps, one for private entities and one for municipalities and other governmental entities. Each cap is at 3 percent of the utility’s highest historical peak load, but the rules that apply to each cap differ slightly.
A net metering facility under the private cap may have a generating capacity up to 2 MW, while a facility under the public cap may have a generating capacity up to 10 MW (each municipality may not exceed 10 MW for all of its departments or subdivisions combined), but is limited to 2 MW per unit. Last year, the Massachusetts DPU issued guidance defining a “unit” as a single turbine for wind facilities, a single piece of generating equipment (e.g., an engine or turbine) for agricultural net metering facilities, or a single inverter for solar net metering facilities.
The Massachusetts DPU defined “facility” for both the public and private caps as “energy generating equipment associated with a single parcel of land, interconnected with the electric distribution system at a single point, behind a single meter.” This three-part test, however, poses problems for larger capacity projects, particularly those under the public cap, which can potentially have a capacity of up to 10 MW. For larger projects, the distribution company that performs the System Impact Study and designs the interconnect might conclude that a design using multiple points of interconnection is best for safety, electrical reliability and electrical efficiency. While a design with two points of interconnection and two meters might be more appropriate, a facility with more than one point of interconnection will not qualify for net metering credit. The Massachusetts DPU’s definition thereby encourages suboptimal interconnection configurations.
The Massachusetts DPU has recognized the problem its definition caused and is currently considering a fix. In October 2012, the Massachusetts DPU sought comments on whether to allow an exception on the basis of optimizing facility interconnection and how such an exception might work. In response, the local distribution companies tepidly supported an exception to the DPU’s three-part test, emphasizing a clear and workable definition of “facility,” while other commenters were more enthusiastic about an exception. There is no set timeline for the Massachusetts DPU to make a final decision on whether to grant an exception. Since the definitional order was issued, a number of petitions have been filed seeking exemptions from various aspects of the DPU’s rule, and some petitions have met with success.