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NYISO interconnection

New York ISO coordinates interconnection studies with connecting transmission owners through its Standard Interconnection Procedures and applicable study paths.

Guide updated October 9, 2026.

Start with Attachment HH​

For the current cluster framework, use Open Access Transmission Tariff Attachment HH. It addresses the application window, customer engagement, study phases, decision periods, and related processes. Do not use an older Attachment X or Class Year summary as the governing checklist for a new cluster request. FERC's July 2026 order documents accepted updates to the Attachment HH framework. Attachment HH revision order

Start at NYISO's Interconnections page for current notices, forms, and submission instructions. Identify whether the project seeks a new interconnection, a change, or a service-specific request. Follow the current routing for that request type, including the Interconnection Projects Portal where directed.

Define the service and application inputs​

Keep Energy Resource Interconnection Service (ERIS) and Capacity Resource Interconnection Service (CRIS) distinct in the project record. A CRIS-only request has a different purpose from a request to connect a new facility. Use the current form and process instructions for the selected path. The Attachment HH records identify separate interconnection-request and CRIS-only forms.

For preparation, gather:

  • Company and project identity, contacts, selected request type, and requested dates.
  • Technology, generating equipment, storage configuration, and capacity values with units.
  • Requested ERIS and CRIS quantities where applicable.
  • POI, connecting transmission owner, voltage, location, and proposed electrical arrangement.
  • Site evidence, technical attachments, models, drawings, and financial records.

Create an input register that records what each value means and where it came from. For storage, distinguish energy capacity from power, charging demand from injection, and individual-unit capability from a shared plant limit.

Prepare for technical review​

Use the current application instructions to identify model and drawing deliverables. For an efficient internal review, organize generating-unit information, transformer parameters, collector-system data, plant controls, reactive capability material, and supplier documentation around a single equipment revision.

The one-line and geographic layout should describe the same proposed POI and plant configuration. Record equipment assumptions explicitly, especially when procurement decisions remain open. Maintain a model manifest with supplier version, software dependencies, operating conditions, and test evidence.

NYISO's cluster process includes physical-infeasibility review and coordination with connecting and affected transmission owners. A conceptual route or substation label should therefore be supported by enough project information to explain the proposed arrangement; it is not evidence that connection space has been confirmed. Cluster-process revision order

Manage site evidence and financial decisions​

Use the current Attachment HH provisions, forms, and window notice for site-control evidence, study funding, readiness deposits, and decision-period obligations. Record deadlines as project-specific actions, with a responsible person and evidence of completion. Current interconnection resources

For internal preparation, associate the plant layout and gen-tie route with the corresponding site documents. Keep outstanding land questions separate from confirmed rights. Track deposits, invoices, and security independently, including the obligation they satisfy and any acknowledgement received.

Use any pre-application information as an input to development decisions, with its stated limitations. It should not be represented internally as study approval, a reserved POI, or an accepted interconnection request.

Review the submission and its revisions​

Recommended preparation checks include:

  1. Reconcile requested service, facility ratings, export assumptions, and storage operation.
  2. Match the POI and transmission owner across forms, models, drawings, and maps.
  3. Preserve the link between equipment changes and updated technical files.
  4. Record each outstanding information request and the exact response submitted.
  5. Retain the full dated submission, payment evidence, and portal acknowledgement.

Check each action against the current process rather than assuming an earlier cycle's response period or form remains applicable.

Official sources and scope​

Use NYISO Interconnections for current resources and the Attachment HH revision order and linked tariff records for the documented cluster framework. The Interconnection Projects Portal is the official portal referenced in NYISO's submission materials.

This guide supports preparation and navigation. The effective tariff, current cycle instructions, and project-specific transmission-owner requirements control. A completed checklist does not establish application acceptance or compliance.