UK G98 Microinverter Procurement: An ENA Connect Direct Supplier Checklist

A UK microinverter quotation should begin with the connection route, not a generic claim that the product is “G98 ready.” Under Engineering Recommendation G98, the simplified route applies to fully type-tested micro-generation connected at low voltage up to and including 16 A per phase. The total installed arrangement, not the wattage of one module or one microinverter, determines whether that route is appropriate.

For importers, distributors and OEM buyers, the practical task is to match the exact saleable model to its ENA Connect Direct record, supporting Type Test Verification Report and intended Distribution Network Operator (DNO) process before committing stock.

This checklist supports supplier due diligence. It does not replace the current EREC documents, ENA assessment, electrical design, DNO decision or competent installer responsibility.

Classify the project before promising G98

Record the AC registered capacity of every generating unit and storage device that can operate in parallel with the distribution network. Calculate aggregate current per phase and include existing equipment at the premises. Do not classify a project from the nameplate of a single unit.

Project condition	Commercial action
No more than 16 A per phase and fully type tested	Confirm current G98 and DNO notification route
More than 16 A on any phase	Treat as a G99 pre-application case
Export limitation is proposed	Confirm whether G100 evidence and DNO approval are required
Generation plus battery storage	Review combined operating modes and aggregate capacity
Several nearby premises in one rollout	Check the DNO multiple-premises procedure before installation

National Grid's published G98 procedure describes 16 A per phase as approximately 3.68 kW at 230 V, but the current calculation and applicable network requirements control. Use the grid voltage and phase pre-quotation guide to document the supply arrangement before selecting the route.

Freeze the exact model identity

The Connect Direct entry, report, product label, invoice and supplied unit should describe the same product. Record manufacturer, brand, full model and suffix, rated AC power and current, phase arrangement, hardware revision and firmware baseline.

Family certificates and visually similar housings are not enough. A different suffix can represent another power rating, relay, communications module or grid profile. Require a controlled model schedule that maps every orderable SKU to the relevant system reference.

Identity checkpoint	Evidence to retain
Manufacturer and brand	Connect Direct record and signed report
Full model and suffix	Model schedule, label artwork and datasheet
Registered capacity/current	Report value and rating label
Hardware and firmware	Approved baseline and release record
Manufacturing site	Certificate/report scope and change agreement

Add an exact-model clause to the purchase order. Substitution should require written technical review before production or shipment.

Verify the Connect Direct status, not only the search result

The ENA's 2025 Distributed Generation Connection Guide explains that the former Type Test Register functionality moved to Connect Direct. Manufacturers upload and maintain product information, while the ENA assesses the submission. A newly submitted device can show Awaiting Assessment; the guide also distinguishes compliant and non-compliant outcomes.

For each proposed model:

1. Find the exact manufacturer, model and suffix in the public device search.
2. Record the system reference number and registered capacity.
3. Confirm the applicable EREC route and current compliance status.
4. Download the accessible Type Test Verification Report and supporting documents.
5. Save a dated PDF or screenshot of the reviewed entry for the RFQ file.
6. Recheck status immediately before production release and shipment.

Do not market an awaiting-assessment entry as approved. A database match without a compliant status and traceable evidence is not a shipment gate.

Review the Type Test Verification Report as an engineering record

The report should identify the exact product and demonstrate the required G98 tests, not merely state compliance in a sales declaration. Cross-check rated values, protection functions, operating parameters, test equipment, laboratory or responsible test party, report references and manufacturer declaration.

The evidence review should cover at least:

• Loss-of-mains and interface-protection behavior
• Voltage and frequency operating limits
• Reconnection behavior and timing
• Power quality, including harmonics and DC injection where applicable
• Active-power response and other required control functions
• Model identity, firmware and connection options used for testing
• Manufacturer declaration that production units remain equivalent to the tested design

Use the anti-islanding evidence guide to separate a single protection test from the complete grid-interface evidence pack.

Separate product registration from the DNO connection process

A compliant device record supports a connection application or notification; it does not approve every site. GOV.UK guidance separates connect and notify from apply to connect. Installers using the G98 route generally notify the relevant DNO within 28 days after installation, while G99 applications require approval before installation. The actual route must be confirmed for the site and current DNO procedure.

The supplier should request enough project data to avoid misclassification:

• Installation postcode and responsible DNO
• MPAN where required by the installer or application
• Existing generation, storage and EV bidirectional equipment
• Single-line diagram and point of connection
• Unit quantity, AC rating and phase allocation
• Proposed export limit and control method
• Single-premises or coordinated multi-premises rollout

Make the quotation conditional when these inputs are missing. Do not promise a DNO response date, Smart Export Guarantee eligibility or MCS outcome from the inverter record alone.

Build a distributor-ready UK document pack

One controlled pack should let the importer, installer and DNO trace the product without requesting unrelated files from several contacts.

1. Connect Direct entry and system reference
2. Complete Type Test Verification Report
3. Datasheet and UK rating-label artwork
4. Installation, commissioning and user manuals in clear English
5. Grid-profile selection and protection-setting instructions
6. Firmware baseline and controlled change log
7. Declaration of Conformity and applicable product-safety/EMC evidence
8. Warranty terms and identifiable UK service contact
9. Model/SKU cross-reference and approved accessories
10. Sample single-line diagram and installer handover checklist

Keep product conformity, grid connection, installation certification and incentive requirements as separate workstreams. One logo or certificate should never be used as shorthand for all four.

If the saleable system includes Wi-Fi, a gateway, app or cloud service and is offered to consumers, assess the UK connected-product security regime separately. The UK PSTI Wi-Fi microinverter importer checklist covers credentials, vulnerability reporting, security-update periods and the Statement of Compliance; a G98 record does not answer those questions.

Control production changes after listing

The ENA guide notes that substantive changes to G98 or G99 requirements may require updated testing and reassessment. Product changes can create the same traceability problem. The supplier agreement should require notification before changing grid-control firmware, sensing circuits, relays, power stage, communications hardware, enclosure, connectors, label, model designation or production site where conformity may be affected.

For firmware releases, document the affected functions, test impact, approved baseline, rollback or recovery route and fleet deployment plan. The firmware change-control guide provides a distributor workflow.

Receiving inspection should sample exact model and suffix, label values, firmware or batch traceability, manual revision, connector set and carton identity. Quarantine any unexplained deviation instead of treating it as a cosmetic supplier change.

Put evidence gates into the RFQ and purchase order

Use staged commercial release points:

1. RFQ gate: DNO, voltage, phase, unit count, existing equipment and export requirement recorded
2. Evidence gate: exact Connect Direct entry, compliant status and report reviewed
3. Sample gate: label, firmware, connectors, manuals and monitoring configuration matched
4. Production gate: controlled BOM and approved UK document revisions frozen
5. Shipment gate: register status rechecked and receiving plan issued

Supply for UK grid-connected projects is conditional on confirmation of the exact model and suffix, current ENA Connect Direct compliance status, applicable G98/G99/G100 route, aggregate capacity per phase, responsible DNO process and final site design. Hardware, firmware, label or manufacturing changes require written review before shipment.

Next step for a UK microinverter RFQ

Send the installation postcode, DNO, supply voltage and phase, module datasheet, proposed microinverter quantity, existing generation/storage, export requirement and target order volume through TMG Contact. TMG can organize an exact-model evidence matrix and controlled sample review; the ENA, DNO, qualified designer and installer retain their respective assessment and connection responsibilities.

For private-label supply, review the OEM microinverter manufacturer solution before fixing the UK brand, model designation, label and warranty chain.