If you have looked into rooftop solar, you will have come across the Smart Export Guarantee — the scheme under which energy suppliers pay households for surplus solar electricity exported to the grid. Rates vary but can add meaningfully to the financial return on a rooftop system. It is a reasonable question to ask whether plug-in solar can access the same payments. Currently it cannot, and understanding why is useful context.
What the Smart Export Guarantee requires
The SEG is administered by Ofgem. To access export payments, a solar system must be MCS-certified — that is, installed by a Microgeneration Certification Scheme-registered installer using MCS-certified equipment. MCS certification is the quality assurance framework for domestic renewable energy installations in the UK.
Plug-in solar systems, as currently defined, cannot achieve MCS certification. The reasons are structural: MCS certification is designed for permanently installed systems wired directly into the property’s consumer unit. Plug-in solar connects via a standard socket and is portable. It does not fit the MCS framework.
What happens to the surplus you generate
Any electricity your plug-in solar system generates that your home does not immediately use flows back to the grid through the socket. Without a Smart Export Guarantee arrangement, this happens without payment. From a financial perspective, this surplus is essentially donated to the grid.
This is why self-consumption matters so much for plug-in solar. The more of your own generated electricity you use directly — by being home during daylight hours or by storing it in a battery — the better your financial return. Our battery storage guide covers how a battery changes this equation.
Could plug-in solar access SEG payments in the future?
Possibly. As the plug-in solar market develops, there is a reasonable case for a simplified export payment scheme for small plug-in systems. Germany does not currently pay for plug-in solar exports, but the discussion is ongoing there too. The UK government has been willing to update regulations quickly for plug-in solar when the case is made, and if the market grows as fast as Germany’s did, a simplified export scheme becomes more politically viable.
For now, assume no export payments and maximise self-consumption. That assumption gives the most conservative and realistic picture of your financial return. Our savings guide and calculator both work on this basis.