Interconnection of Renewables to Electric Transmission: Insights from Industry Expert Tim Taylor

Tim Taylor is a HeatSpring instructor who focuses on utility transmission and distribution systems, and the interconnection of renewables to those systems.

We recently asked Tim a few questions about two new courses that he has been developing.

Tim’s new course, “Introduction to Transmission” is live on HeatSpring.  “Interconnection of Solar PV to Transmission” is scheduled to go live in June 2024.  You can sign up for either course separately or sign up for both courses in a discounted course bundle on HeatSpring.

Why is an understanding of electric transmission critical to the interconnection of utility-scale renewable projects to transmission?

Three significant barriers to transmission interconnection of renewables require a knowledge of transmission systems or the transmission providers:

• Interconnection requirements and costs as well as transmission upgrade costs
• Length of time from project submittal to commercial operation, including time spent in the interconnection queue
• Timing uncertainty for the completion of required system upgrades

To reduce those risks and to efficiently navigate the transmission interconnection process requires that resources working in transmission have at least a basic knowledge of transmission.

What makes understanding the transmission industry challenging?

First, there are a lot of players in transmission.  This includes transmission owners and transmission providers which may be Independent System Operators/Regional Transmission Operators (ISOs/RTOs), investor-owned utilities, or government agencies, as well as state and federal regulators.  Building new transmission lines and substations also involves landowners and local/state agencies and organizations.

Second, transmission infrastructure is a regulated industry, although there has been some effort to make parts of it more competitive.  At the federal level, the primary entity is the Federal Energy Regulatory Commission (FERC) which regulates the transmission and sale of wholesale electricity in interstate commerce.  The non-profit North American Reliability Corporation (NERC) also plays an important role, as it develops and enforces reliability standards for most of the North American bulk power system (large generating stations and transmission facilities).  At the state level, Public Service Commissions (PSC’s) play key roles, while at the local level numerous entities are involved, particularly in siting and permitting. 

Third, about 2/3 of US electric load is served by ISOs and RTOs, which operate several different types of wholesale electric power markets.  The other 1/3 of electric load is served by more traditional utility models, such as vertically integrated utilities and government-owned utilities.  It’s important for resources in the renewable energy industry to understand how these structures and entities work, since they have a large impact not only on transmission access, but also on a renewable facility’s revenue streams.

What are interconnection queues?

Due to the very high reliability expectations for US bulk power systems, a transmission provider needs to understand the impact that proposed renewable energy projects will have on its system before interconnecting them.  The transmission provider goes through a series of technical studies of their system with the proposed generation connected.  In doing so, they identify upgrades to the transmission system that are required due to the new generation.    

Because there has been such a flood of generation interconnection requests over the last five years, and a limited number of resources that perform these studies, transmission providers have had to create interconnection queues to organize when each renewable project will be studied.  You can think of the interconnection queue as a waiting line, or backlog, of proposed projects waiting to be studied, although it’s more complicated than that.

It’s important for developers to understand this interconnection study process, the different tasks/studies that are performed, and the process milestones of both the transmission provider and the developer.  While the different transmission providers in the US have different procedures, at a high level there is much in common.

Presently transmission providers’ interconnection processes are relatively dynamic, partly due to FERC Order 2023 “Improvements to Generator Interconnection Procedures and Agreements”, which was issued in July of 2023.  In addition, in May 2024 it is anticipated that FERC will issue a final ruling on “Building for the Future Through Electric Regional Transmission Planning and Cost Allocation”, which will have some impact on generation interconnections.  That Notice of Proposed Rulemaking was issued in April 2022.