UK Power Networks (UKPN) is the Distribution Network Operator for London, South East England, and East England — one of the most densely connected and capacity-constrained network areas in the UK. Whether you are installing a rooftop residential system in Essex or a commercial ground-mount in Kent, the G98 or G99 process with UKPN is the gateway to a legal, grid-connected installation.
This guide covers the full UKPN application process: service territory, the connections portal, G98 notification, G99 application stages, export limitation requirements, timelines, and connection costs.
UK Power Networks Service Territory
UKPN operates three distribution networks across three licence areas:
- London Power Networks — Greater London
- South Eastern Power Networks — Kent, East Sussex, West Sussex, Surrey, parts of Hampshire
- Eastern Power Networks — Essex, Hertfordshire, Bedfordshire, Cambridgeshire, Suffolk, Norfolk
Together, these three networks serve approximately 8.1 million homes and businesses — around 28% of the UK population. Solar installers in these areas deal exclusively with UKPN for grid connection applications.
If you are unsure whether a specific postcode falls under UKPN, use the postcode lookup at ukpowernetworks.co.uk. Border postcodes — particularly around the Midlands and northern home counties — should always be checked, as SP Energy Networks and NGED serve adjacent areas.
G98 vs G99: Which Applies to Your System?
The Engineering Recommendations G98 and G99 govern different system sizes:
| Criterion | G98 | G99 |
|---|---|---|
| Export capacity per phase | Up to 16A (≈3.68 kW single-phase) | Above 16A per phase |
| Prior approval required | No — notify within 28 days | Yes — approval before installation |
| Typical residential system | Most 3–4 kW systems | 4+ kW single-phase, commercial systems |
| Commissioning test required | No | Yes |
For a detailed breakdown of the differences, see the G98 vs G99 comparison guide.
Most residential installations in London and the South East fall under G98. However, installers pushing system size to reduce battery charging costs or maximise export earnings must check phase current limits carefully — exceeding 16A per phase moves the installation into G99 territory.
The UKPN Connections Portal
All UKPN generation connection applications are handled through the online portal at connections.ukpowernetworks.co.uk.
The portal allows you to:
- Run a generation connection enquiry to check network capacity at a specific address
- Submit G98 notifications
- Submit G99 applications and upload supporting documents
- Track application status in real time
- Accept or decline a Connection Offer
- Submit commissioning test results
You will need to register for a portal account as an installer or agent. UKPN recommends using the same account for all projects to keep a consolidated application history.
Pro Tip
Always run a Generation Connection Enquiry before preparing a full G99 application. The enquiry takes approximately five working days and tells you whether the local network has capacity for the proposed generation, and whether export limiting will be required. This avoids investing time in a detailed application only to receive restrictive Offer conditions.
G98 Notification Process for UKPN
For systems up to 16A per phase, G98 applies. The process is:
- Install and commission the system in accordance with G98 and MCS standards.
- Within 28 days of commissioning, log in to the UKPN connections portal and submit a G98 notification.
- Provide: installation address, inverter make and model, G98 type-test certificate reference, installed capacity (kW), and installer MCS certificate number.
- UKPN will acknowledge the notification. No Offer or approval is issued under G98 — the notification is informational only.
The installer is legally responsible for submitting the notification, not the system owner. Failure to notify is a breach of the distribution licence conditions.
G99 Application Process for UKPN
For systems above 16A per phase — covering most commercial systems and larger residential systems — G99 applies. No installation may begin until UKPN has issued a formal Connection Offer and it has been accepted.
Stage 1: Generation Connection Enquiry
Submit a generation connection enquiry on the UKPN portal. Provide the site address, proposed installed capacity, and the connection voltage level (LV or HV). UKPN will respond within approximately five working days with an initial capacity assessment.
Stage 2: Full G99 Application
Submit the full G99 application through the portal. Required documents:
- Completed G99 application form (available on the portal)
- Single-line diagram showing inverter, protection, metering, and isolation arrangements
- Site layout drawing
- Inverter datasheet with G99 type-test certificate (or confirmation of G99 compliance)
- Earthing arrangement details
- Protection relay settings and test certificates (for systems requiring dedicated protection)
- Planning permission reference or permitted development confirmation
- For systems over 50 kW: Protection and Automation report prepared by a competent engineer
Document Checklist
Incomplete applications are the most common cause of delay. UKPN will not begin technical assessment until all required documents are received. Use solar design software to generate compliant single-line diagrams and equipment schedules directly from your system design — this reduces preparation time and ensures the documents meet UKPN’s formatting requirements.
Stage 3: UKPN Technical Assessment
UKPN’s connections team reviews the application against network capacity and technical standards. For straightforward LV connections in areas with available capacity, this stage runs within the 45-working-day target. For:
- Systems requiring HV connection
- Sites in constrained network areas (particularly inner London)
- Systems triggering network reinforcement requirements
…the assessment may extend beyond 45 working days. UKPN is required to keep you updated on progress during any extension.
Stage 4: Connection Offer
UKPN issues a formal Connection Offer document. The Offer sets out:
- Approved connected capacity (kW)
- Any export limitation conditions (see below)
- Required protection and metering specifications
- Connection cost breakdown (see below)
- Offer acceptance deadline (typically 30 days)
Review every clause of the Offer before accepting. Once accepted through the portal, the Offer is binding.
Stage 5: Installation and Commissioning
Install the system in accordance with the accepted Offer conditions, G99, and IET Wiring Regulations (BS 7671). On completion, carry out the G99 commissioning tests. For the full test procedure, see the G99 commissioning test guide.
Submit commissioning test results to UKPN via the portal, along with the completed Commissioning Declaration. UKPN will formally register the generation unit on their network database.
UKPN Export Limitation Requirements
Export limiting is more frequently applied by UKPN than by most other DNOs, particularly in the London Power Networks area. The reasons are structural: London’s low-voltage network was designed primarily for dense load demand, not distributed generation. In areas with high solar penetration or constrained transformer capacity, UKPN routinely issues Offers with export limitation conditions.
Common export limitation conditions in UKPN areas:
| Condition | Meaning |
|---|---|
| Export limit: 0 kW | System may self-consume but cannot export to grid |
| Export limit: X kW | Maximum continuous export capped at stated level |
| Dynamic Export Limiting | Export varies in real time based on network availability |
Export limitation at 0 kW is common in:
- Inner London postcodes with high existing generation density
- Areas served by transformers already operating near rated capacity
- Some urban South East areas with constrained LV infrastructure
If a 0 kW export limit is proposed and the project economics depend on export income, consider requesting an alternative Offer with a modest export allowance, or explore battery storage to shift generation to self-consumption.
Warning
Do not assume you can export to the grid until you have a signed Offer from UKPN confirming the export limit. Some installers quote export tariff income to customers before receiving the Offer — if the Offer includes a 0 kW export condition, this creates a contractual dispute. Always confirm the export condition before making financial projections to customers.
UKPN Network Reinforcement
For larger systems — typically above 50 kW at LV or any HV connection — UKPN may determine that the existing network requires reinforcement before the connection can be made. Reinforcement might involve:
- Upgrading the local distribution transformer
- Installing or reconductoring LV cables
- Upgrading protection and switchgear
Reinforcement costs are shared between UKPN and the applicant. The Connection Offer will include a cost estimate and a proposed programme schedule. Reinforcement work is carried out by UKPN; the applicant pays the agreed contribution before work begins.
Timeline for projects requiring reinforcement typically runs 3–9 months beyond the standard 45-working-day assessment window. Plan project programmes accordingly.
Connection Costs for G99 in UKPN Areas
UKPN charges connection costs based on the technical work required. For standard LV G99 connections (residential or small commercial, no reinforcement), typical costs are:
| System Size | Indicative Connection Cost |
|---|---|
| Up to 50 kW LV | £500–£2,500 (application and meter work) |
| 50–100 kW LV | £1,500–£5,000 |
| 100 kW–1 MW LV/HV | £5,000–£30,000+ depending on reinforcement |
These figures are indicative. The actual cost is determined by UKPN’s network assessment and will be stated in the Connection Offer. Costs include UKPN’s administration, technical assessment, any new metering, and any civils or plant work UKPN must carry out.
Cost Recovery
Under Ofgem rules, UKPN must refund a portion of connection costs if a larger connection is made within five years that uses the same network reinforcement. Keep records of your connection application and Offer — you may be entitled to a partial refund if the local network is subsequently upgraded.
Using Solar Design Software for UKPN Applications
Preparing a UKPN G99 application involves compiling accurate technical documentation from a complete system design. Using solar design software that produces G99-compliant single-line diagrams, equipment schedules, and protection settings directly from the design model removes a manual step that commonly introduces errors.
With solar software, you can:
- Generate single-line diagrams that meet UKPN’s document requirements
- Produce accurate installed capacity calculations for the application form
- Model self-consumption and export scenarios to advise customers on export limitation impacts
- Create professional proposal documents alongside the technical compliance pack
This reduces application preparation time and minimises the risk of UKPN returning an application as incomplete.
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UKPN Contact Information
| Contact Purpose | Details |
|---|---|
| Generation connections portal | connections.ukpowernetworks.co.uk |
| General connections enquiries | 0800 029 4285 |
| UKPN main website | ukpowernetworks.co.uk |
| ENA Engineering Recommendations | energynetworks.org |
UKPN’s connections team operates Monday to Friday, 09:00–17:00. For urgent operational matters (not application queries), contact their 24-hour network operations line.
Related Compliance Resources
- G98 vs G99: Which Applies to Your System?
- G99 Application Guide — Full Process
- G99 Commissioning Test Requirements
- NGED: G99 Solar Application Guide — Midlands, South West, Wales
- Northern Powergrid: G99 Application Guide — North East England, Yorkshire
- UK Solar Compliance Overview
Frequently Asked Questions
How long does a G99 application take with UK Power Networks?
UK Power Networks targets a response within 45 working days for standard G99 applications. Complex applications requiring network reinforcement or those in constrained urban areas such as inner London may take longer. Starting early and submitting a complete application package reduces delays significantly.
Do I need to notify UKPN for a G98 installation under 16A per phase?
Yes. Under G98, you do not need prior approval, but you must notify UK Power Networks within 28 days of commissioning. Notification is submitted through the UKPN connections portal. The installer, not the homeowner, is responsible for filing the notification.
Does UKPN require export limitation in London?
In many parts of inner and central London, UK Power Networks applies export limitation conditions to new G99 connections due to network capacity constraints. Export limiting to 0 kW or a reduced level is commonly required. Always confirm the specific condition in your Offer letter before proceeding.
What documents are required for a UKPN G99 application?
A standard G99 application to UKPN requires: a completed G99 application form, single-line diagram, site layout, inverter datasheet and G99 type-test certificate, earthing arrangement details, protection relay settings, and planning permission reference (if applicable). For systems over 50 kW, a Protection and Automation report is also required.
