Smart Export Guarantee (SEG) and plug-in solar

The Smart Export Guarantee (SEG) is an Ofgem scheme under which some licensed electricity suppliers pay small-scale generators for the electricity they export to the grid. It is the route many rooftop solar households use to earn a little for the surplus they do not use themselves. A natural question for anyone considering plug-in solar is whether the same payments could apply.

The honest answer today is that it is unsettled. The SEG normally involves a certified installation and eligible export metering, and it is not clear that a self-installed plug-in system would meet those conditions. We set out what the scheme involves below, and where the open questions lie.

What is the Smart Export Guarantee?

Under the SEG, certain larger licensed suppliers are required to offer a tariff that pays eligible small-scale generators for electricity exported to the grid. The scheme is overseen by Ofgem, but the rates and terms are set by individual suppliers rather than fixed centrally, so the offer you can get depends on which supplier you apply to. You do not have to take an export tariff from the same supplier you buy electricity from.

What conditions and metering are usually involved?

Export payments depend on knowing how much electricity actually leaves your home, so eligibility normally rests on two things: an installation that meets the relevant standards, and a meter that can measure exports — typically a smart meter able to take half-hourly export readings. Without an eligible meter, there is no measured export figure for a supplier to pay against. Generation connected to the network is also normally notified to the distribution network operator under the relevant engineering recommendation.

On the certification side, Ofgem's guidance is specific: for solar PV up to 50kW, demonstrating a suitably certified installation normally means presenting a Microgeneration Certification Scheme (MCS) certificate or an equivalent. MCS certification covers installations carried out by an accredited installer, which is the practical sticking point for a system you set up yourself — see the note below.

Would self-installed plug-in solar qualify?

This is the open question. The conditions above were written with certified, professionally installed systems in mind. Because MCS certification rests on installation by an accredited installer, a system you set up yourself would not normally have it — and a plug-in system that connects through a socket may not have the export metering the scheme expects either. That is why we cannot say it would earn export payments. Whether plug-in systems will be brought into the SEG is not addressed by the new regulations, so nothing is confirmed.

What this means for your numbers

Because export eligibility for plug-in solar is uncertain, it is safest to assume no export income at all. For that reason our calculator defaults export earnings to zero, and any savings it shows come from the electricity you use while it is being generated rather than from selling surplus. If the rules later allow plug-in systems to take part in the SEG, that would be an upside on top of self-use savings, not something to count on now. For the mechanics of how surplus power even reaches the grid, see our guide on whether plug-in solar can export to the grid.