In April 2007, Maryland enacted legislation ([http://mgaleg.maryland.gov/2007RS/chapters_noln/Ch_119_sb0595E.pdf S.B. 595]) requiring the Maryland Public Service Commission (PSC) to form a small generator interconnection working group to develop interconnection standards and procedures that are "consistent with nationally adopted interconnection standards and procedures," and to revise the state's interconnection standards and procedures on or before November 1, 2007.
The Maine Public Utility Commission (PUC) adopted interconnection procedures in January 2010. These rules apply to all transmission and distribution utilities operating in the state and apply to all distribution generation (not just renewables). Maine's interconnection procedures, based in part on the Interstate Renewable Energy Council Inc. 2006 Model Interconnection Procedures,* identify four different tiers with corresponding technical screens. These are:
In November 2005, the Indiana Utility Regulatory Commission (IURC) approved rules governing the interconnection of distributed generation (DG). Indiana's interconnection rules require the state's investor-owned utilities to provide three levels of interconnection to customer-generators.
Hawaii has established simplified interconnection rules for small renewables and separate rules for all other distributed generation (DG). For inverter-based systems up to 10 kilowatts (kW) in capacity (and inverter-based DG under 250 kW on islands other than Kauai), there is a simple application process for interconnection. Systems must use inverters compliant with IEEE 1547 and UL 1741.
In July 2006 the District of Columbia Public Service Commission (PSC) initiated a formal inquiry into the development of uniform interconnection procedures for on-site distributed generation systems. The PSC subsequently concluded that an interconnection standard was feasible and continued with the rule making process, culminating with the adoption of final interconnection regulations in February 2009 (DC PSC Order No. 15182).
In December 2007, the Connecticut Department of Public Utility Control (DPUC) now called the Public Utilities Regulatory Authority (PURA) approved new interconnection guidelines for distributed energy systems up to 20 megawatts (MW) in capacity. Connecticut's interconnection guidelines apply to the state's two investor-owned utilities -- Connecticut Light and Power Company (CL&P) and United Illuminating Company (UI) -- and are modeled on the Federal Energy Regulatory Commission's (FERC) interconnection standards for small generators.*
In December 2005, the Colorado Public Utilities Commission (PUC) adopted standards for net metering and interconnection, as required by Amendment 37, a renewable-energy ballot initiative approved by Colorado voters in November 2004. The PUC standards generally apply to utilities with 40,000 or more customers and all cooperative utilities.* [http://www.leg.state.co.us/CLICS/CLICS2008A/csl.nsf/fsbillcont3/062FC08A... H.B.
'''''Note: The California Public Utilities Commission (CPUC) approved a [http://docs.cpuc.ca.gov/EFILE/MOTION/162852.PDF proposed settlement] in September 2012, enacting the first fundamental redesign of Rule 21 since 2000. The complete revised Rule 21 Tariff, as described at a high level below, can be found beginning on page 136 of CPUC Decision 12-09-018. The individual tariffs adopted by the utilities can be found on the CPUC web site above. '''''
The South Carolina Public Service Commission (PSC) adopted simplified interconnection guidelines for small distributed generation (DG) in December 2006. These guidelines address renewable-energy systems and other forms of DG up to 20 kilowatts (kW) in capacity for residential systems, and up to 100 kW for non-residential systems. Provisions for three-phase generators are not included.