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How much of my solar electricity will I export?

Short answer

Solar you don't use or store as it's generated is exported. MCS lookup tables suggest a typical home with no battery uses only 15–39% of its solar and exports the rest. A 5 kWh battery raises that to about 50–76%. Exports earn a Smart Export Guarantee rate: untied tariffs averaged 4.39p in 2024/25, and several now pay 12p or more.

Last checked 24 September 2026 · 3 sources

In more detail

  • Export = generation − self-consumption.
  • MGD 003 values (3,300-3,599 kWh generation): out all day 15-18% self-use without battery; home all day 24-39%.
  • SEG needs an MCS (or equivalent) certificate and an export-reading smart meter; rates are set by suppliers and must be above 0p.
  • DNOs can cap export (G99), which can limit how fast a battery can export.

The facts, dated

  1. 01
    Ofgem SEG Year 5: average untied / tied rate — 4.39 / 14.54 p/kWh

    scheme · GB · checked 24 September 2026 · Ofgem

  2. 02
    SEG Year 5 payments / export — £56.97m / 443.1 GWh

    scheme · GB · checked 24 September 2026 · Ofgem

  3. 03
    Outgoing Octopus flat export rate from 1 Mar 2026 — 12.0 p/kWh

    market_data · GB · checked 24 September 2026 · Octopus Energy

  4. 04
    EST: 'around 12p' per exported unit typical — 12 p/kWh

    market_data · GB · checked 24 September 2026 · Energy Saving Trust

What we saw in the field

[QA review 2026-09-24] H-6 CONTRADICTS (consolidated verdict): export 857 kWh > PVGIS June 2023 total generation ~808 kWh. £173/857 kWh = ~20p, consistent with Flux export, so likely a longer billing period or battery export. Supersedes 'consistent' in | Earlier notes: Homeowner (SW England, 5.6 kWp: 4.0 SW + 1.6 NE, 15 kWh battery, did not export from the battery) reported June 2023 export of 857 kWh with 20 kWh import. PVGIS 5.3 hourly data for June 2023 near Exeter give TOTAL generation of about 808 kWh (619 SW + 189 NE, 14% loss), and MCS annual sums (zone 4) ~5.2 MWh/yr. Exporting 857 kWh in one month while also running the house is IMPLAUSIBLE as stated. Possible explanations: a billing period longer than June, export including battery discharge, or a misremembered figure. The 20 kWh import is plausible for a battery-backed June. Customer 1's DNC/G99 export cap of 5 kW because of local solar saturation is consistent with DNO practice (not verified here).

Sources

Last checked: 24 September 2026