Half-hourly settlement and what it means for solar owners
If you export under SEG you have been settled half-hourly all along — that was always a condition of getting paid. The reform under way now is to the other side of your meter, and what it changes is the value of using your own electricity at the right time of day.
If you are paid under the SEG , your export has been settled half-hourly from the start. Ofgem’s guidance requires an export meter capable of half-hourly measurement, with an export MPAN . Nothing about that changes.
The reform under way — market-wide half-hourly settlement — is about the import side: how suppliers are charged for what their customers use. Central systems went live in September 2025 and migration runs to May 2027.
What it changes for you is indirect but real: accurate half-hourly import data is what makes time-of-use pricing workable, and time-of-use pricing changes what your own generation is worth at different times of day.
What is actually being reformed
Historically, domestic electricity was settled against profile classes — an assumed shape for how a typical household uses electricity across the day. Your supplier was charged against that assumed shape rather than against what you personally did.
Market-wide half-hourly settlement replaces the assumption with your meter’s actual half-hourly readings.
Settlement is how suppliers are charged for the electricity their customers use. It is not how you are charged.
The reform does not, by itself, put you on a time-of-use tariff, change your unit rate, or require anything of you. It changes the incentives and the information available to the people who design tariffs.
Where the migration has got to
| Date | Milestone |
|---|---|
| 22 September 2025 | Central systems live — ready to accept migrating MPANs. The load shaping service became operational |
| 22 October 2025 | Supplier meter migration began, across an 18-month window |
| 16 February 2026 | Elexon reported more than two million meters transitioned |
| October 2026 | Elexon’s plan targets roughly 80% of meters accepted |
| 7 May 2027 | End of meter migrations |
| 2 July 2027 | Cut over to the shorter settlement timetable |
The final step is worth a note because it is the point of the exercise for the industry: settlement currently takes around 14 months to complete and is intended to fall to about four. That reduces how long suppliers carry uncertainty about what they owe, which is a cost that ends up in tariffs.
Why solar exporters were never in profile classes
This is the part that gets muddled in most coverage, so it is worth stating plainly.
Ofgem’s SEG guidance requires that “the renewable export from an eligible installation must be metered”, that the meter “must be capable of taking half-hourly measurements and have an export MPAN”, and that it is located where the installation connects to the network.
So a SEG-eligible export arrangement was half-hourly by construction. The reform is not extending half-hourly settlement to your exports; they were never anywhere else.
What this means practically:
- Your SEG payments do not change because of MHHS
- Your export MPAN does not change
- You do not need a new meter for export purposes
- If your supplier offers a time-varying export tariff, that was already possible
What does change, and why it matters for solar
The import side of your meter is where the reform lands, and it matters to solar owners for one reason: it makes time-of-use import pricing easier to offer and price accurately.
That interacts with solar in a way that is not automatically in your favour.
A solar household’s import is shifted into the evening and into winter — precisely because the daytime and summer demand is being met by the roof. Evening and winter are when time-of-use tariffs are typically most expensive. So the shape solar gives you is not obviously the shape a time-of-use tariff rewards.
Against that, accurate half-hourly data makes it easier for suppliers to offer products built around shifting demand into daylight — which is exactly the lever that raises self-consumption, and self-consumption is worth roughly six times export.
What to do
Nothing, for the migration itself. Your supplier handles it.
Check your smart meter is set to half-hourly readings if you want the data. Many are set to daily by default. You can usually change this in your account, and it is your data.
Get your half-hourly data before evaluating any time-of-use tariff. It is the only way to answer the question properly, and it is free.
Do not confuse this with your export arrangement. If somebody tells you that half-hourly settlement means you need to change your SEG tariff or your export meter, that is not right. See our SEG table for what is actually available.
Sources
- Market-wide Half Hourly Settlement and the BSC
- More than two million meters have now transitioned to half-hourly settlement
- Smart Export Guarantee: Guidance for Generators
- MHHS change request CR061: alignment of M10 go-live delivery date
Contains public sector information licensed under the Open Government Licence v3.0.
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