Station Capacity Calculator

For micro-embedded, small, mid-size and large Distributed Energy Resources (DER) facilities

As part of Hydro One's modernization of digital tools, our revamped Station Capacity Calculator is now live below. The new tool offers the same functionality and test criteria as our previous Excel-based version, but with a web-based, mobile-friendly interface.

In Q3 2025, we will also be launching a DER Capacity Map to provide customers easy access to a geographic representation of system capacity information. Stay tuned!

We're here to help you

For technical help, please contact our Distributed Connections group at: 1.877.447.4412 Email us

photo of workers touring a Hydro One transformer station

To determine whether there is sufficient capacity to connect your proposed DER, enter all specific details in the calculator below and press the "Check Capacity" button to see the result.

Important information for applicants, consultants and contractors

We remind applicants NOT to incur major project related expenses until they receive an offer to connect from our team.
The Station and Feeder Capacity Calculator automatically tests a proposed connection using four criteria based on our Technical Interconnection Requirements for Micro-Embedded Generator Projects (microFIT TIR). Applicants who receive a “Pass” result through the calculator remain subject to capacity constraints due to the timing of when we receive their completed Form C application.
Applicants please carefully read "Explanations of test criteria and results for proposed DER connections" and the "Terms of Use" below prior to using the calculator.
Data included in the calculator is only applicable to our customers and NOT intended to evaluate connections to other Local Distribution Companies.
Users are required to enter our station and feeder for their proposed DER connection. If you require this information, please contact our Distributed Connections group. Project information such as station and feeder names are only provided to our customers, consultants or contractors with valid DER project numbers and who are listed as a project contact in our records.
The information may be stale-dated as soon as it is posted and should be used for information purposes only. The calculator does not allocate capacity or reserve capacity. This can only be done upon completion of an offer to connect from our team.
We provide only the base capacity information for the transformer stations it owns. The capacity table on the Independent Electricity System Operator’s (IESO’s) website reflects this information as well as any existing and contracted generation facilities and capacity reserved for other programs (such as the 2 MW reservation for the microFIT Program). Please consult the IESO website for evaluating capacity availability.

Explanations of test criteria and results for proposed DER connections

If there is available capacity for your proposed DER connection at the station and feeder the calculator will output “Pass”. If you wish to continue with an application for a microDER connection, please apply using the Micro-Generation Connection Application (FORM C). We remind applicants NOT to incur major project related expenses until they receive an Offer to Connect from our team.

If there is no available capacity for your proposed connection the calculator will output “Fail”. The following are the test results and explanations if there is no capacity for your connection:

Feeder Capacity Test Failed — This test checks feeder generation capacity limitations on the distribution system. This project failed because there is no available capacity on the feeder(s) connected to Hydro One’s upstream distribution or transformer station. The maximum acceptable generation limit for connection to the feeder has already been reached. This limit maintains operability, respects system constraints and avoids unacceptable feeder voltage and power quality issues.

Station Thermal Capacity Test Failed — This test checks for available thermal capacity at the upstream distribution or transformer station. This project failed because there is no available thermal capacity at the upstream station.

Micro Generation Capacity Test — This test checks available capacity for micro generation on the feeder. This respects system limits, and avoids unacceptable feeder voltage and power quality issues. Please see our Bulletin for more information.

Important note: A proposed micro-embedded project connection may fail this test while a project greater than 10 KW may pass at the same station and feeder. The Station & Feeder Capacity Calculator takes into account that the projects greater than 10 kW will have certain connection requirements which will be performed at the expense of the customer. A Connection Impact Assessment (CIA) is performed for such projects to identify the connection requirements and the associated estimated costs.

Short Circuit Capacity Test — This test checks for available short circuit capacity at the upstream distribution station and transformer station. This project failed because there is no available short circuit capacity. The short circuit limits such as equipment limits and Transmission System Code limits at the upstream station must not be exceeded by the addition of generation facilities.

Terms of use

Hydro One Networks Inc. (“Hydro One”) is pleased to provide this capacity calculator (“Calculator”) to assist generators in providing capacity information. While we believe this Calculator will be a helpful tool, we caution you that this Calculator and the information contained in or generated by it (collectively the “Materials”) are provided to you for your information only. In that the Calculator has been established only to provide estimated capacity information, Hydro One is not in a position to confirm its completeness, timeliness, or accuracy. In addition, Hydro One may, from time to time, make changes to the Materials without notice. Please note that information regarding capacity availability may not be current. In no event shall Hydro One be liable for any damages of any kind related to the use or misuse of the Materials. Hydro One is not making any representations of any kind or nature, and disclaims all warranties, whether express or implied, in respect of the Materials, including the implied warranties of fitness for a particular purpose, merchantability, expectation of privacy and non-infringement. Notwithstanding your use of the Materials or the information generated by this Capacity Calculator. Please note that Hydro One is not allocating Capacity for your project based on the use of this tool.