DNO export limits for UK commercial solar — 2026
DNO export consents are the single most common physical constraint on UK commercial solar sizing in 2026. Where the local network has limited capacity to accept new export, DNO offers may include zero-export, time-limited export, or fully constrained export consents. Each scenario changes project economics materially. Understanding the constraint shapes the right system size and storage strategy.
How export consents work
DNO export consent is granted as part of G99 connection offer. The DNO assesses local network capacity and grants permission to export up to a specified limit. Common consent patterns:
- Full export consent — system can export up to its full nameplate capacity. Best case; rarely available on industrial estates with constrained networks.
- Limited export consent — system can export up to a specified MW limit (often well below nameplate). Common on industrial estates; system size capped at ~70-80% of physical capacity.
- Zero-export consent — system can connect but not export. Self-consumption only. Material economic impact on systems sized for export.
- Conditional export consent — export permitted only outside specific times of day or under specific network conditions. Often combined with active network management requirements.
Economic impact of export constraints
Export consent affects project economics through three mechanisms:
- SEG revenue loss — exported energy at SEG tariff (5-15p/kWh) is direct revenue. Zero-export consent eliminates this revenue line.
- Self-consumption ceiling — without export, marginal kWh value falls to zero (curtailed). System size must match self-consumption capacity, typically reducing optimal sizing 20-40%.
- Capex efficiency — fixed soft costs (DNO fees, structural surveys, design) are similar regardless of system size. Smaller size means worse £/kWp economics.
Worked example: a site with 600 kW peak demand and full export consent might support 1 MWp solar (8% export at 7p SEG = £4k/year revenue). Same site with zero export consent supports only 600 kWp solar (no surplus to curtail). Loss of 400 kWp capacity ~ £64k/year of avoided cost saving and £4k/year of SEG revenue.
Mitigation strategies
Where DNO constrains export, three mitigation strategies typically apply:
- Battery storage — battery time-shifts surplus generation to overnight or evening consumption. Effectively converts curtailed export to self-consumption. £400-550/kWh capacity. Project IRR uplift typically 3-8 percentage points on export-constrained sites.
- Active power factor / curtailment systems — automated systems that limit export when network conditions require. Required by some DNOs as condition of consent. Costs £8-25k.
- Demand-side management — operational changes to align load with generation (e.g. shift battery charging to midday, run cold-storage compressors during solar peak). Free or low-cost; meaningful self-consumption uplift on flexible operations.
- Smaller system sizing — accept smaller capacity matching self-consumption. Sub-optimal economically but simplest contractually.
Technical FAQs
How do I know what export consent my DNO will offer?
Can I appeal a low export consent?
Does battery storage always solve export constraints?
How does export consent affect SEG eligibility?
What's changing on UK DNO export capacity?
Related guides
DNO export limits: why they matter for commercial solar
Distribution Network Operators (DNOs) control the UK low-voltage and high-voltage electricity distribution network. When you install commercial solar, the electricity you generate but cannot use on-site is exported to the grid — and the DNO must manage this flow to maintain network stability. Export limits are constraints on how much electricity your installation can export.
For most small commercial systems (under 50kWp, single phase), export is straightforward with a G98 notification. For larger systems, export limits set by the DNO can significantly affect the economics of your installation — limiting how much excess generation you can export and therefore earn from.
How export limits are set
G98 systems (under 50kWp, single phase)
These systems notify the DNO but do not require approval. Export is typically unrestricted at this scale, subject to normal network capacity constraints.
G99 systems (above 50kWp or multi-phase)
These require formal DNO application and assessment. The DNO reviews local network capacity at your connection point and sets an export limit based on available headroom. This limit may be significantly below your system generation capacity.
Zero export connections
Some network nodes have no available export capacity, particularly in rural areas and industrial zones with high embedded generation. DNO may offer a connection with zero permitted export — meaning all generated electricity must be consumed on-site.
Export limit scenarios and their impact
| Scenario | System size | DNO export limit | Economic impact |
|---|---|---|---|
| Unrestricted export | 200kWp | 200kW | Optimal — all excess generation earns SEG income |
| Partial export limit | 200kWp | 100kW export limit | 50kW excess generation wasted at peak; reduce with battery storage |
| Low export limit | 200kWp | 30kW export limit | Significant curtailment needed; battery essential to maximise value |
| Zero export | 200kWp | 0kW export | All generation must be consumed on-site; battery critical for weekend/holiday generation |
| Export limit with active control | 500kWp | Variable up to 200kW | DNO may permit higher export during off-peak periods; active power control required |
Working with export limits
Battery storage
The primary solution to export limitation. A 50–200kWh battery stores excess midday generation and dispatches it when consumption is high (evenings, mornings), reducing curtailment and improving self-consumption to 80–95%.
Demand shifting
If your business can shift some electricity-intensive processes (EV charging, refrigeration pre-cooling, equipment charging) to solar peak hours, you increase on-site consumption and reduce the generation that hits export limits.
Export limit inverter control
Modern inverters include active power control (APC) functionality that can automatically curtail output to stay within DNO export limits. This prevents export limit breaches without hardware addition, but wastes curtailed generation.
DNO reinforcement (negotiated)
If your site has potential for larger solar installation but export capacity is limited, you can fund network reinforcement works to increase export headroom. Costs £20,000–200,000+ but may be worthwhile for large systems (500kWp+).
Pre-application DNO engagement
Before committing to a solar system design, always obtain a pre-application DNO enquiry for systems above 50kWp. Costs £500–1,500 but provides a budgetary estimate of connection costs and identifies export limit constraints before detailed design work begins. DNOs in England and Wales are: UK Power Networks (South/East), Western Power Distribution (Midlands/SW/Wales), Northern Powergrid (NE England), Electricity North West, SP Energy Networks (Scotland/NW England).
In Scotland, SP Energy Networks and SSE Networks handle the majority of connections. Each DNO has different processes and timelines — check their specific guidance before submitting applications.
DNO export limits by network: UK commercial solar 2026
Every UK Distribution Network Operator (DNO) applies export limits on commercial solar connections to protect grid stability. The limit is set at the G99 connection approval stage and specifies the maximum export in kW that the inverter is permitted to push back to the grid. Export limits vary significantly by DNO, substation area, and local network load profile. The table below summarises the typical thresholds and processes for each of the six GB mainland DNOs.
| DNO | Coverage area | Typical export limit (commercial) | G99 pre-application | Constrained areas |
|---|---|---|---|---|
| UK Power Networks (UKPN) | London, South East, East Anglia | Full export common in EoE; constraints in Central London and coastal Kent/Sussex | UKPN online portal — 4–6 weeks | Central London, coastal ME/CT/BN postcodes at peak summer |
| National Grid Electricity Distribution (NGED) | Midlands, South West, East Midlands, Wales | Generally good headroom; SW rural areas increasingly constrained from agri-solar | NGED capacity tool + formal enquiry — 4–8 weeks | Rural Cornwall, Herefordshire/Shropshire, parts of E.Midlands |
| Electricity North West (ENW) | NW England (Lancashire, Cumbria, Manchester, Cheshire) | Good industrial headroom; some rural Lancashire constraints | ENW pre-application — 4–6 weeks | Rural Lancashire/Cumbria |
| Northern Powergrid (NPg) | Yorkshire, North East England | Strong export headroom in urban/industrial areas; rural Yorks increasingly constrained | NPg capacity map + application — 4–8 weeks | Rural North Yorkshire, parts of East Yorkshire |
| SP Energy Networks (SPEN) | Central/South Scotland, Merseyside/N.Wales | Scotland generally unconstrained; Merseyside pockets constrained | SPEN G99 enquiry — 4–8 weeks | Parts of Merseyside/North Wales |
| Scottish and Southern Electricity Networks (SSEN) | North/South Scotland, South England (Hampshire, Dorset, Oxfordshire, Thames Valley) | South England increasingly constrained from solar PV build-out; N.Scotland good | SSEN pre-application — 4–8 weeks | Hampshire coast, Dorset, parts of Oxfordshire |
How to check your site's specific export headroom
Every DNO publishes network capacity data and a pre-application enquiry route. The process for checking your site's export headroom has three stages:
Stage 1: Check the DNO capacity map
Most DNOs now publish a public-facing network capacity map (heat map) showing available DG (distributed generation) headroom by substation area. UKPN, NGED, ENW, and Northern Powergrid all have these tools. Look for the 'available DG capacity' layer in your postcode area. Green or amber areas typically have headroom for commercial-scale solar; red areas indicate constraints. This is a screen-level check only — it does not replace a formal pre-application enquiry.
Stage 2: Submit a G99 pre-application enquiry
For commercial solar above 50kWp, submit a formal G99 pre-application enquiry to the relevant DNO. Include: site address, proposed system capacity (kWp), expected peak export (kW), connection voltage (LV or HV), and commissioning date. The DNO responds with an initial assessment of available export capacity and whether a full G99 application, load flow study, or reinforcement works are likely. Pre-application typically costs £250–£500 and takes 4–8 weeks. This is the definitive check before committing to system design.
Stage 3: Formal G99 application and technical assessment
If the pre-application is positive, submit the full G99 application. For systems above 50kWp, a formal technical assessment is required (fee £500–£2,500 for commercial scale). The DNO will confirm the Maximum Export Limit (MEL) for your connection — this is the hard ceiling on export that your inverter must be programmed to respect. Commissioning is not permitted until G99 approval is issued in writing. Timeline from application to approval: 4–16 weeks depending on DNO and network complexity.
Export limit workarounds: 4 approaches compared
If your G99 assessment returns a lower Maximum Export Limit than your system would naturally export, there are four main workarounds. The right choice depends on system size, budget, and whether your DNO offers flexible connection products.
| Workaround | How it works | Cost | Best for | Trade-off |
|---|---|---|---|---|
| Battery storage with active export management | Battery absorbs excess solar at moments of grid constraint; inverter reduces export to MEL | £400–£600/kWh installed (2026) | Sites with high self-consumption + SEG income potential | Capital cost of battery; battery size must match curtailed export volume |
| G100 Flexible Connection | DNO curtails your export electronically via smart switch during grid stress events; you export freely at all other times | Usually free from DNO; inverter must be G100-compliant | Urban/industrial sites where grid events are rare | DNO can curtail during peak demand; revenue loss during curtailment events (typically <50hrs/year) |
| Demand side response (DSR) | Increase on-site consumption at moments of high solar output (EV charging, heat pumps, HVAC) to reduce export below MEL | Cost of DSR-controllable loads — may already exist on site | Sites with flexible controllable loads (EV fleet, manufacturing, refrigeration) | Requires active energy management system |
| Network reinforcement (DNO-led) | DNO upgrades the local substation to create more export headroom | DNO quotes cost; may be partially shared or fully funded | Sites where no workaround is practical; large industrial installations | Expensive (£50k–£500k+); long timeline (12–36 months); requires formal connection agreement |
DNO export limits and your commercial solar finance
DNO export limits directly affect the financial case for commercial solar. A lower Maximum Export Limit (MEL) reduces SEG income and may reduce the self-consumption model's attractiveness if the building's consumption profile doesn't match peak solar output. Lenders pricing commercial solar finance will ask for the G99 approval letter as part of the technical due diligence pack; without it, finance drawdown cannot proceed.
| Finance route | How export limit affects it | What to show the lender |
|---|---|---|
| Green loan (capital purchase) | Lower MEL reduces energy savings forecast; lender adjusts IRR calculation | G99 approval letter; energy model showing self-consumption vs export split |
| Operating lease or finance lease | Lessor underwrites system performance — lower MEL = lower guaranteed output; may affect lease rate | G99 approval; independent yield assessment (P50/P90 basis) |
| Power Purchase Agreement (PPA) | Developer owns system; developer manages G99 and export risk. MEL is developer's problem, not yours | PPA developer handles DNO submission; you just need grid connection confirmation |
| PSDS grant (public sector) | Salix and PSDS appraise MEL as part of technical review; low MEL can affect grant scoring | G99 pre-application result; battery storage proposal if MEL is low |
Step-by-step: what to do if your G99 returns a low export limit
(1) Ask the DNO for the reason — is it local substation capacity, protection settings, or a thermal constraint? Different causes have different solutions. (2) Request a G100 flexible connection offer — most DNOs now have this as a standard product. (3) Get a battery storage quote to match the curtailed export volume — battery often makes the project financially viable even with a low MEL. (4) Check if the self-consumption case alone (without any export) still gives an acceptable payback — many large commercial buildings consume all their solar output on-site anyway. (5) If none of the above works, request a reinforcement quote — but budget 12–36 months and £50k–£500k+ for the DNO to do the work.
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