Technical guide · DNO export consents

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?
Submit G99 application; DNO returns a conditional connection offer including export consent terms. Pre-application enquiry (free, 4-6 weeks) provides indicative consent without committing to formal application. Most large commercial solar projects start with pre-application to confirm export capacity before committing to detailed design.
Can I appeal a low export consent?
Limited appeal options. Network reinforcement (paid by you) can lift export consent in some cases. Active network management may allow higher peaks with active curtailment. Most DNO consents are technically determined by network capacity; commercial appeal isn't typically available.
Does battery storage always solve export constraints?
Not always. Battery storage works for short-duration export curtailment (hours within a day). For seasonal export curtailment (network can't accept summer generation regardless of time), battery doesn't help — the constraint is total annual energy, not instantaneous. In those cases, smaller system size or demand-management solutions are the answer.
How does export consent affect SEG eligibility?
SEG only applies to actually exported energy. If consent permits export, SEG applies; if zero-export, SEG isn't applicable. Lost SEG revenue is a real economic loss when consent is constrained. Factor into project economics at design stage, not post-installation.
What's changing on UK DNO export capacity?
OFGEM RIIO-ED2 (2023-2028) prioritises distribution network upgrade for energy transition. Many DNOs are accelerating capacity upgrades; some industrial estates that had zero-export consents in 2023 now offer limited or full export. Worth re-applying every 12-18 months on previously constrained sites.

G99 connection process

Full DNO application process and timeline.

Solar export limits Q1 2026

Specific 2026 patterns across UK DNOs.

Battery storage finance

When battery solves export constraints economically.

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