UC Berkeley

Electric transmission system operators (ISOs, RTOs, and utilities) require large new generators and storage resources seeking to connect to the grid to undergo a series of impact studies before they can be built. This process establishes what new transmission equipment or upgrades may be needed before a project can connect to the system and assigns the costs of that equipment. Berkeley Lab has collected interconnection cost data from interconnection studies from the New York Independent System Operator (NYISO), representing at least 43% of all new unique generation and storage resources requesting interconnection in NYISO from 2003 through 2019. Project-level cost summary data are available for download on this page. We find: -Average interconnection costs have grown as the number of interconnection requests have escalated. -Upgrades both at the point of interconnection and in the broader network have driven cost increases. -Applicants still actively working through the interconnection process have higher interconnection costs than historical projects, but lower costs than projects which have recently withdrawn or been completed. -Solar projects tend to have higher interconnection costs than other resource types. -Larger generators have greater interconnection costs in absolute terms, but economies of scale exist on a per kW basis for solar and wind projects. -Cost estimates increase as projects complete more studies in the interconnection process. Berkeley Lab will publish a series of short analytical papers of generator interconnection costs to the transmission system for MISO, PJM, SPP, ISO-NE and NYISO, which you can find at https://emp.lbl.gov/interconnection_costs.