The point of interconnection (POI) is the defined electrical connection point between a generating project’s connection facilities and the relevant utility or transmission network. Its exact meaning comes from the applicable agreement and technical documents. It identifies an interface; it is not automatically the same location as the revenue meter, property line or change in equipment ownership.
For a solar project, establishing that point helps align engineering, connection studies and contractual responsibilities.
Why the definition belongs in the project documents
Different agreements and system contexts use related terms such as point of connection, point of common coupling and point of change of ownership. They should not be substituted without checking their definitions.
A FERC interconnection-facilities order explicitly distinguishes the point of interconnection from the point of change of ownership within its large-generator agreement context. This historical example demonstrates the distinction; current project obligations must come from the applicable agreement and tariff.
Mark the relevant points on the one-line and reference the governing definitions. A diagram with a label but no agreed meaning can leave the same ambiguity as a contract without a drawing.
Several boundaries may exist
| Boundary | What it identifies |
|---|---|
| Point of interconnection | Defined network connection interface |
| Ownership boundary | Where responsibility for owned assets changes |
| Metering point | Where specified electricity quantities are measured |
| Control or performance point | Where a required operating value is assessed |
| Property boundary | Legal land boundary, which may not match electrical interfaces |
Some points can coincide. Do not assume they always do. Their relationship affects losses, construction scope, access and operating responsibilities.
An illustrative plant connection
A solar plant connects through a collector system, transformer and dedicated line to a utility substation. The connection agreement identifies the POI at a particular network interface, while the ownership boundary lies elsewhere along the connection facilities.
The EPC contract must then establish who designs and builds each section, who supplies protection and metering, and who maintains the relevant assets. A phrase such as “complete interconnection included” is insufficient if those boundaries remain unclear.
This example is conceptual. Actual arrangements can be simpler or more complex and must be documented individually.
Capacity and performance need a location
A plant’s DC module rating is not its output at the POI. Inverter capacity, internal losses, auxiliary consumption and any operating limits can affect what reaches the connection point.
If an agreement specifies export or reactive-power requirements at a location, the design must evaluate behavior at that location. Measuring a different point without accounting for the intervening system can produce an incorrect conclusion.
FERC’s interconnection explainer provides context for studying new generation connections. The applicable provider’s documents determine the actual study and performance requirements.
Clarify the interface before equipment procurement
The project team needs the proposed connection location, voltage, equipment arrangement, ownership boundaries and relevant control and protection requirements. Utility information and study findings can affect plant design.
Changes to the connection point may affect routes, equipment duties, approvals and costs. Treat them as coordinated project changes rather than edits to a single drawing.
The owner’s responsibility matrix should also cover access, outage coordination, testing and ongoing operation. Construction completion does not resolve those duties automatically.
Start with the governing definition, then the drawing
Project teams often use familiar electrical terms as shorthand. That is convenient until two parties attach different meanings to the same abbreviation. A developer may use POI to describe the planned utility connection, while a supplier refers to an equipment terminal within its own scope. Unless the documents resolve that difference, both parties can believe they have addressed the interface.
Begin by identifying the agreement, tariff or technical document that governs the term for the project. Then show that defined point on the electrical drawings and reference it consistently in specifications. If the project uses related terms, include their definitions rather than assuming they are synonyms.
This is a coordination task with legal and engineering consequences. The drawing explains the physical arrangement, while the agreement establishes applicable responsibilities and requirements. Neither should be interpreted in isolation when the two appear inconsistent. Resolve the discrepancy through the responsible project parties before it influences procurement or construction.
Ownership, operation and maintenance can have different boundaries
Owning an asset does not automatically answer every question about who operates it, maintains it or authorizes work near it. Those responsibilities may be allocated separately in the project documents. Access rights and required coordination can also extend beyond a simple ownership line.
For each interface asset, identify the owner, operator, maintenance responsibility and approval process for relevant work. This is especially useful for metering, communication equipment, protective devices and facilities connecting the plant to the wider network. The exact allocation depends on the project.
A responsibility matrix should point to the controlling documents. It should not create new obligations by informal assumption. If a procurement package says that a connection facility is excluded, the owner needs to know which other contract includes it. Otherwise, a gap may remain between a completed generating plant and the facilities necessary for its authorized connection.
The nearest electrical line is not a confirmed connection
A site can appear attractive because a line or substation is nearby. Physical proximity is relevant to route planning, but it does not establish that the network can accept the proposed generation or that the visible facility is the appropriate connection voltage or ownership context.
The relevant provider’s process evaluates the proposed connection and its effects. Available information may be preliminary, conditional or subject to study. A site-selection discussion should preserve those distinctions rather than turning a promising location into an assurance of connection capacity.
FERC’s interconnection overview explains the role of studying generation connections in its jurisdictional context. Distribution-level and other projects can follow different governing processes. Owners should establish which provider and procedure apply to their project instead of assuming a national description supplies the local application rules or schedule.
Capacity at the array is not capacity at the connection point
A solar project’s module rating describes DC nameplate capacity. Power delivered at a defined grid interface depends on the conversion equipment, internal network, operating conditions and applicable limits. The difference is not simply a matter of changing the unit label from DC to AC.
A project may have several useful capacity figures: module DC rating, inverter AC rating, transformer ratings and a permitted export limit. The contract and design should identify which figure applies to each obligation. A statement that the plant is a particular number of megawatts is incomplete if the measurement basis is omitted.
This distinction also affects acceptance evidence. If a requirement is assessed at the POI, measurements taken elsewhere must be interpreted with the intervening system in mind. The project team should define the measurement approach before testing, including how relevant losses and auxiliary loads are treated. That prevents disagreement about whether two parties are evaluating the same performance.
Reactive-power requirements need a defined location too
Real power and reactive power describe different aspects of the electrical operating condition. A requirement concerning reactive capability or voltage behavior must identify where it is evaluated and under which conditions. Equipment capability at inverter terminals does not automatically establish the same capability at a remote network interface.
The electrical system between those locations can affect the result. The appropriate engineering studies should represent the actual plant and connection arrangement. Equipment selection, control design and the required operating range need to be considered together.
An owner reviewing a proposal should ask where the stated capability applies and what evidence supports it. A generic inverter data sheet is not a complete plant-level demonstration. The final design and acceptance plan must connect the equipment capability to the requirement in the governing project documents, with any assumptions and unresolved conditions made explicit.
Metering is a separate design and commercial question
The revenue meter may be installed at the POI, near it or at another defined location. The agreement should explain what is measured and how that measurement is used. If the commercial quantity refers to a different point, the treatment of intervening losses or other adjustments must be established by the applicable arrangements.
Metering also involves equipment, communications, access and data responsibilities. The project needs to identify who supplies the meter and associated components, who approves the design and who receives the data. Those interfaces can affect the physical design and handover schedule.
For a buyer, the useful question is not merely “Is a meter included?” Ask whether the proposed scope satisfies the actual metering requirements and whether related equipment and communications are included. A plant production dashboard can be useful for operations without being the contractual revenue measurement system. Keep those purposes distinct in documentation and performance reporting.
Protection and controls cross organizational boundaries
A connection can require coordination between plant equipment and network equipment. Protection, communications and controls may depend on information or actions from several parties. A project schedule should recognize those interfaces rather than treating each cabinet or relay as an isolated deliverable.
Identify who develops the required settings and logic, who reviews them, who implements them and how the completed functions will be demonstrated. The applicable requirements determine the scope; a glossary cannot supply universal settings or test procedures.
The responsibility matrix should also address later changes. A control adjustment within the plant can affect behavior at the connection interface. A network change can require review of the plant’s assumptions. Record the process for evaluating and authorizing relevant modifications so the operating team does not rely solely on knowledge held by the original construction staff.
A changed POI can be a material project change
Moving the connection location can alter the route, equipment arrangement, voltage basis, study assumptions and third-party interfaces. It may also affect land rights, access arrangements and construction planning. The significance depends on the specific change and governing process.
Before accepting a revised point, the project team should identify which documents and decisions are affected. Update the one-line, responsibility matrix, study inputs, procurement packages and schedule where necessary. Do not assume that changing one drawing automatically updates every dependent contract or calculation.
A useful change record explains the reason, the affected scopes and the remaining approvals. It should distinguish a proposed revision from an accepted one. This is particularly important when procurement must proceed before every external condition is resolved. The owner should understand which assumptions are being relied on and the consequence if those assumptions change.
Construction completion and permission to operate are different milestones
A contractor can complete installation while external approvals, required testing or other connection conditions remain outstanding. The project schedule should distinguish physical completion, test readiness, acceptance and authorization for the intended operating state.
This separation helps the owner understand what a progress report actually means. “Ready to energize” should have a defined basis and responsible decision maker. It should not be used interchangeably with “all work is finished” or “commercial operation has begun.” Actual milestone definitions come from the contracts and applicable provider requirements.
Plan the evidence required at each stage. Drawings, test results, approved settings, operating documentation and other deliverables should be assigned to responsible parties. A complete handover makes the interface understandable to the team that will operate the facility, including any temporary restrictions or unresolved items that remain in force.
Build a concise connection-interface register
A useful register brings the important boundaries into one coordinated reference. Include the governing POI definition, drawing reference, connection voltage, capacity basis, ownership boundaries, metering location and principal operating responsibilities. Link each entry to its source document and revision.
The register should also identify open decisions and their owners. It is better to show an unresolved metering interface clearly than to leave readers to infer that a blank means no requirement exists. Review the register when the design, agreement or study findings change.
This document does not replace the contract or engineering package. It helps the project team find and reconcile the relevant information. For developers and procurement teams, that clarity can make proposals easier to compare and scope gaps easier to identify before they become construction or operating disputes.
Common questions
Is the POI always at the meter?
No. Metering and interconnection points can differ. Read the agreement and drawings to establish their relationship.
Is it the same as the point of common coupling?
Not automatically. Point of common coupling has its own technical context in relevant standards. Use each term according to the governing definition.
Can the POI be selected solely by proximity?
No. A nearby line or substation does not establish connection suitability or available capacity. The relevant provider must evaluate the proposal through its process.
What should an EPC proposal state?
Identify the connection point, asset boundaries, included facilities, external work and acceptance responsibilities. State unresolved assumptions clearly.
Align the plant and grid interface
Discuss connection documents and development status with Soleil Energy’s utility-scale solar team. Coordinate relevant substation and distribution work through its power infrastructure scope.
Project requirements depend on the site, equipment and applicable rules. Confirm design and installation decisions with the appropriate qualified professional.
