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ENERGY SYSTEM DEVELOPERS

INTERCONNECTION STEPS AND APPLICATIONS FOR LARGE DG SYSTEMS AND GRID RESOURCES

Medium to large Distributed Generations (DG) systems and grid resources—generally classified in sizes ranging from 500kW up to 10 MW or more—require more detailed technical evaluation of their potential impact to the Oncor grid. Results of these evaluations are described in an impact study that details the estimated costs and facility upgrades required for interconnection and safe reliable operation with the grid.

 

Common modes of operation for these types of systems include non-exporting parallel operation with closed transition switching that occurs in less than 100 milliseconds, systems with extended transfer switching to facilitate "peak shaving" or "demand management" and dispatchable grid resources supplying power and ancillary services. 

 

Oncor works with energy storage developers, solar farms, and developers of conventional backup generation with export capability to the grid—to facilitate the smooth integration of these customer and grid resources while ensuring safe and reliable operation of the transmission and distribution electric grid.

THE INTERCONNECTION PROCESS

Generally 9-12 Months for Most Large-Scale DG Projects. Time Frame Will Change Depending on the Size of a Project.

Kickoff Steps: Generally 45-90 Days

Step 1 - Contact Oncor for prescreen options and project classifications

Step 2 - Prepare and submit application, technical drawings and sequence of operations

Step 3 - Participate in project kickoff meeting with Oncor functional departments and ERCOT as required

Studies and Contract Steps: Generally 45-90 Days

Step 4 - Provide funding for the Tariff Pre-Interconnection Study and additional studies as required

Step 5 - Review engineering design and study results describing the required system upgrades and cost estimates

Step 6 - Secure appropriate agreements and fund project to proceed

Construction, Commissioning and Testing Steps: Generally 45-90 Days

Step 7 - Coordinate construction, commissioning, telemetry and relay testing as required to proceed to commercial operation

Step 8 - Finalize project requirements and begin commercial operation upon receiving written approval from Oncor

RESOURCES

DOWNLOADS

Filename
Electric Service Guidelines 2021.pdf
Size
1 MB
Format
application/pdf

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Oncor Interconnection Application - Small Induction and Non-Certified In....pdf
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1 MB
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application/pdf

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Oncor Interconnection Application Generation Paralleling Longer than 100....pdf
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1 MB
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application/pdf

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Oncor Interconnection Application for DGR and DESR.PDF
Size
923 KB
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application/pdf
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Oncor Interconnection Application for Certified Systems.pdf
Size
989 KB
Format
application/pdf
Filename
Oncor Interconnection Application for Certified Systems.pdf
Size
989 KB
Format
application/pdf
Filename
Oncor Interconnection Application for DGR and DESR.PDF
Size
923 KB
Format
application/pdf
Filename
Oncor Interconnection Application for Certified Systems.pdf
Size
989 KB
Format
application/pdf

Filename
Oncor Interconnection Application for Certified Systems 500 kW or Greate....pdf
Size
1 MB
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application/pdf

FREQUENTLY ASKED QUESTIONS

Due to the complexity of interconnecting large-scale DG projects, an impact study must be performed and will be at the customer’s expense. Based on the results of the impact study, customer costs will be determined for system upgrades deemed necessary to complete the interconnection of the project.

Due to the complexity of interconnecting large-scale DG projects, an impact study must be performed. Customers should allow six to eight weeks for the completion of this study. Based on the results of the impact study, upgrades or changes may need to be made to the transmission or distribution equipment and in some cases this equipment may have long lead times. In addition, some changes may require clearances which cannot be scheduled during high-load periods and could result in project delays. Oncor will work with customer schedules and provide expected construction scheduling timelines after funding and securing of proper documentation.

Upon request, Oncor will perform prescreens prior to an impact study. This simple screen will assess the requested generation capacity and determine if there is available distribution capacity at the requested location. Results of prescreens are subject to change and may vary from the findings of the final impact study.

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