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Solutions / Engineering guide
Wind Power Export Limits & Zero-Export Requirements
An export limit concerns power crossing a defined connection boundary. It is different from turbine rated power or the energy a site uses over a billing period. Specify the actual requirement before considering control equipment or describing a project as zero export.
Define the boundary and the requirement together.
Make the permitted export, measurement basis and surplus-energy treatment reviewable before selecting an electrical package.
01 / Meter boundary
Locate the point where export is assessed.
Identify the service connection or other boundary named in the project requirement.
Identify the service connection or other boundary named in the project requirement. A measurement at the wind converter can describe its output while a measurement at the site connection describes the combined exchange of loads and sources. Those are different quantities.
Retain the proposed meter location on the diagram, including other generation or storage paths inside and outside its boundary. An aggregate site value may not describe individual feeders or phases. The relevant authority’s requirement should determine which boundary and measurement basis apply.
02 / Requirement wording
Turn “zero export” into a defined specification.
Record whether the requirement concerns instantaneous power, an averaging interval, energy over a period, or another specified criterion.
Record whether the requirement concerns instantaneous power, an averaging interval, energy over a period, or another specified criterion. Capture permitted values, sign convention, applicable operating states and any stated response or exception conditions from the actual requirement.
Do not invent tolerances or assume that zero energy exported over a billing period means no short-duration export. SMA’s manufacturer-specific zero-export documentation illustrates that active control at the connection point and compatible equipment are part of a defined implementation. It does not establish MARSTON functionality.
03 / Power balance
Separate site demand from available generation.
In a deliberately simplified hypothetical example, generation of 5 kW and simultaneous site demand of 3 kW imply 2 kW of net export before considering other sources, storage and losses.
In a deliberately simplified hypothetical example, generation of 5 kW and simultaneous site demand of 3 kW imply 2 kW of net export before considering other sources, storage and losses. This is an arithmetic illustration, not a MARSTON measurement or an approved control design.
If site demand decreases, an export restriction does not remove the wind resource or establish where surplus energy goes. Define the proposed response and responsible equipment with the integrator. Availability of a potential destination is different from its ability to accept energy in the relevant condition.
04 / Surplus energy
Identify the destination and its limits.
A proposed energy destination could become unavailable or reach its operating boundary.
A proposed energy destination could become unavailable or reach its operating boundary. Record those conditions alongside the candidate’s normal energy paths. Storage capacity, a load label or a generic dump-load reference is not evidence that every surplus event can be handled.
Wind electrical control and turbine protection must be reviewed as an integrated project scope. The dump-load guide explains conditional roles without establishing a MARSTON topology. This page does not define a protection sequence or prescribe a surplus-handling circuit.
05 / Coordination
Include data and control boundaries in the review.
Identify which proposed device observes site exchange, which equipment can change output, and the documented interface between them.
Identify which proposed device observes site exchange, which equipment can change output, and the documented interface between them. A monitor reporting a value is not automatically a controller authorised to act on it.
Specify how unavailable measurements, communication interruptions and equipment constraints are covered by the proposal’s assessment. Record the relevant behaviour and evidence for the selected configuration, rather than assuming a generic network protocol guarantees export compliance.
06 / Acceptance scope
Agree how the claim will be demonstrated.
An acceptance plan should identify the requirement version, connection boundary, selected equipment, relevant site states and the records used to assess the result.
An acceptance plan should identify the requirement version, connection boundary, selected equipment, relevant site states and the records used to assess the result. The responsible project parties define applicable criteria and approved verification activities; this guide does not provide energisation or test procedures.
Keep connection approval separate from a control-function description. Use the grid connection guide for approval inputs and bring the exact export requirement to a technical enquiry. No zero-export product offering or compliance result is confirmed here.
Continue the review with AC & DC Coupling for Wind Hybrid Systems.
Continue the review with Wind Power Self-Consumption & Self-Sufficiency Metrics.
Continue the review with Wind Controller Protocols & Register Maps.
General background: SMA zero-export documentation: manufacturer-specific connection-point control example. These references explain industry concepts; they are separate from the applicable MARSTON product and project documents.
Prepare the information for this review.
Use the checklist to organise the project information. Mark unavailable items and retain document references.
| Review item | Information to provide | Purpose |
|---|---|---|
| Export boundary | Connection point, included branches and measurement location | Define what the value represents. |
| Requirement basis | Permitted behaviour, interval, sign and applicable states | Avoid an ambiguous zero-export label. |
| Surplus paths | Proposed destinations, constraints and responsible equipment | Review energy beyond site demand. |
| Control interfaces | Measurement, output authority and documented coordination | Separate monitoring from control. |
| Acceptance record | Applicable criteria, configuration and responsible reviewer | Define the evidence needed. |
Engineering questions.
Is converter output the same as site export?
No. Site export depends on all relevant sources, loads and losses within the defined connection boundary.
Does zero net exported energy mean zero export at every instant?
No. The assessment interval and permitted behaviour must be stated.
Does this page confirm a MARSTON zero-export package?
No. A specific proposal needs supported equipment, integration review and applicable acceptance evidence.
Can a battery always absorb surplus wind energy?
No. Its operating state, interface and limits require review for the selected configuration.
Can a monitoring protocol prove export control?
No. Measurement semantics, control authority and actual behaviour are separate evidence requirements.
What should accompany an export-limit enquiry?
The exact requirement, connection diagram, other sources, load information and proposed measurement boundary.
Technical enquiry
Bring your project information to the discussion.
An export limit concerns power crossing a defined connection boundary. Share the available information and the equipment scope you want reviewed in a technical quotation.