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Considerations with Distributed Generation: Interconnection

A significant consideration when installing a DG technology is the interconnection of the device to the electric utility system.

Interconnection is the physical connection of on-site generation to the electric utility's distribution grid. It requires the customer and utility to install a variety of relays and monitoring devices on the customer's premises and at the connecting distribution lines to ensure stability and protection of the grid and protection of the customer's site and generation. The complexity and costs of the interconnection tend to increase with the scale of the on-site generation project. The costs of interconnection at the customer's site and required upgrades to the distribution system are paid for by the customer.

Issues related to interconnection that need to be addressed by regulators and utilities before DG markets can thrive include:

  • Technical concerns at the point of interconnection
  • Safety issues posed by grid connection
  • Distribution system reliability impacts
  • Lack of uniform interconnection standards

In the United States, common standards for interconnecting DG devices into the utility system do not presently exist. The lack of common standards is considered a barrier to the wide acceptance and installation of DG technologies.

A key to accomplishing these goals is the Institute of Electrical and Electronics Engineers (IEEE) P1547 Standard for Distributed Resources Interconnected With Electric Power Systems. While intended as a voluntary consensus standard, it is likely to be refined and even adopted in many places.

Those involved in DG applications -- including suppliers, marketers, engineers and end users -- would have a clear set of rules in place across the U.S. Many believe such a standard will lead to wide commercialization of the DG concept and boost many of the specific technologies.