DNO Grid Connection for Farm Solar Panels: Complete UK Guide
The Distribution Network Operator (DNO) connection process is one of the most frequently misunderstood aspects of installing solar panels on farm buildings. This guide explains the process clearly, sets realistic expectations for timescales, and explains how constrained rural networks can affect your installation.
What Is a DNO and Why Do You Need Their Approval?
A Distribution Network Operator (DNO) is the company that owns and operates the electricity distribution network in your area — the cables, transformers, and substations that connect your farm to the National Grid. There are six DNOs in the UK: Northern Powergrid, National Grid Electricity Distribution (NGED, covering the Midlands, South West, and South Wales), Scottish and Southern Electricity Networks (SSEN), SP Energy Networks, UK Power Networks, and Electricity North West.
When you install solar panels, you are adding a generator to the distribution network. Your DNO needs to know about this to ensure the network remains safe and stable, and to record your installation for network planning purposes. The level of notification or approval required depends on the size of your system.
G98 vs G99: Which Application Does Your Farm Need?
G98 Notification
For systems up to 3.68 kW per phase (16A per phase). On a single-phase supply this means up to 3.68 kW total. On a three-phase supply this means up to 11.04 kW total.
- ✓ Simple notification — no pre-approval needed
- ✓ Can install first, notify within 28 days
- ✓ No application fee
- ✓ No waiting period before installation
Rarely applies to farm solar — most agricultural systems significantly exceed these limits.
G99 Application
For all systems above 3.68 kW per phase — which includes virtually every farm solar installation. Covers single-phase above 3.68 kW and three-phase above 11.04 kW.
- ✓ Formal application with technical assessment
- ✓ DNO has 45 working days to respond (small embedded systems)
- ✓ Application fee: typically £500-£2,500
- ✓ Must receive approval before connecting to the network
Required for nearly all farm solar installations above small garden shed arrays.
The G99 Application Process Step by Step
- 1 Prepare technical documentation.
Your installer prepares a single line diagram, site layout, inverter specifications, and proposed export limitation settings. Our team handles all of this as standard.
- 2 Submit the G99 application to your DNO.
Applications are submitted via the DNO's online portal with the technical pack. The application fee is paid at this stage (varies by DNO and system size).
- 3 DNO technical review.
The DNO assesses whether the proposed system can be accommodated on the local network without causing voltage rise or protection issues. This takes up to 45 working days for systems below 1 MW — typically 4-8 weeks in practice for straightforward rural connections.
- 4 Receive connection offer.
The DNO issues a connection offer specifying any conditions, export limitation requirements, or network reinforcement works required. Most straightforward farm installations receive unconditional approval at this stage.
- 5 Accept the offer and install.
Once you accept the connection offer, installation can proceed. After commissioning, we submit the as-built documentation to the DNO and register the system on the MCS database.
Constrained Rural Networks: What Happens When There Is Not Enough Capacity
Rural distribution networks in the UK were designed to deliver electricity to consumers, not to export large quantities of generation. In areas with high solar penetration — such as parts of the East Midlands, East Anglia, and South West — local networks can be constrained, meaning there is insufficient capacity to allow unrestricted export from new solar installations.
When this happens, the DNO may issue a connection offer with one of the following conditions:
- Export limitation: Your inverter is fitted with an active export limiter that prevents export above a specified threshold (often 50% of system capacity). This does not affect self-consumption — it only limits grid export.
- Network reinforcement works: The DNO upgrades the local transformer or network infrastructure to accommodate your system. This work is typically funded by the DNO, but can delay installation by 3-12 months.
- Connection at higher voltage: For very large systems, connection at 11 kV rather than 400V may be required — significantly increasing installation cost.
Our team will identify potential network constraints before you commit to a system design by reviewing your local DNO's interactive heat map (all DNOs are required to publish these) and pre-assessing the likelihood of a constrained connection offer. This allows us to design systems that comply with likely constraints from the outset.
DNO Connection Costs for Farm Solar
| Cost Item | Typical Range | Notes |
|---|---|---|
| G99 application fee | £500-£2,500 | Non-refundable. Varies by DNO and system size. |
| Export limiter device | £200-£600 | Required if DNO imposes export limitation condition. |
| Network reinforcement | £0 (usually) | DNO-funded for constrained networks, but causes delay. |
| Meter upgrade (if required) | £300-£800 | Smart meter needed for SEG — usually free from your supplier. |
How Long Does the DNO Process Take?
For the majority of farm solar installations, the G99 process adds 6-12 weeks to the overall project timeline. In constrained areas, or for larger systems requiring detailed network studies, this can extend to 3-6 months. We recommend starting the G99 application as early as possible in the project — ideally as soon as you decide to proceed, even before the final system design is locked down.
Our team submits G99 applications on the same day that you sign your order, maximising the overlap between the DNO review period and our procurement and planning phase. In most cases, we can arrange installation without any delay caused by the DNO process.
UK Distribution Network Operators by Region
Your DNO is determined by your farm's location. Here is the regional breakdown:
- Northern Powergrid: Northeast England and Yorkshire
- National Grid Electricity Distribution (Western Power Distribution): Midlands, South West England, South Wales
- SSEN (Southern Electric): South of England (excluding London)
- SSEN (Scottish Hydro): North of Scotland and Scottish islands
- UK Power Networks: London, South East England, East Anglia
- SP Energy Networks: Central and Southern Scotland, Merseyside, Cheshire
- Electricity North West: North West England
- Western Power Distribution: East and West Midlands, South West and South Wales (now part of NGED)
We Handle Every Aspect of Your DNO Application
Our team prepares and submits all G99 documentation, monitors the application status, and manages any queries or conditions raised by your DNO. You do not need to contact your DNO directly at any stage of the process — we handle everything from initial submission through to the post-commissioning registration.
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