South Dakota’s interconnection standards for distributed generation, adopted by the state Public Utilities Commission (PUC) in May 2009, apply to customers of investor-owned utilities.* The rules provide for four levels of interconnection for systems up to 10 megawatts (MW) in capacity:
- '''Tier 1''' applies to inverter-based systems up to 10 kilowatts (kW) in capacity that use lab-tested equipment.
- '''Tier 2''' applies to systems up to 2 MW in capacity that use lab-tested equipment.
- '''Tier 3''' applies to systems up to 2 MW in capacity that do not export electricity.
- '''Tier 4''' applies to systems up to 10 MW in capacity that do not meet the requirements of Tier 1, Tier 2 or Tier 3.
Technical screens have been established for each level, and the IEEE 1547 technical standard is used for all interconnections. Reasonable timeframes for application and approval are set forth in the rules. System owners are generally responsible for all interconnection expenses, including interconnection equipment, utility system upgrades and adverse system impacts. Utilities are authorized to require the use of an external disconnect switch. Limited interconnection to area networks is permitted.
General liability insurance is required, with levels that vary by tier. (For Tier 1 systems, only “proof of adequate homeowners, general liability or commercial liability insurance sufficient to insure against all reasonably foreseeable direct liabilities given the size of the small generator facility” is necessary.) For all systems other than residential generators up to 10 kW in capacity, the customer must include the utility as an “additional insured.” The PUC staff may assist with dispute resolution when appropriate.
''* The PUC’s rules do not apply to customers of electric cooperatives or municipal utilities.''