Regulation

Ahead of plug-in solar's 27 August legalisation, an industry analysis warns the UK grid has no reliable way to track how much self-installed capacity is actually connected, pointing to Brazil's estimated 14 GW of undeclared rooftop solar as a cautionary comparison

From 27 August, self-installing up to 800 watts of plug-in solar becomes legal under a connect-first, notify-within-28-days version of the existing G98 process, but the piece argues that self-reporting alone leaves network operators effectively blind to a fast-growing category of distributed generation.

15 August 2026 · Source: Solar Power Portal (opinion, Maya Pindeus, Another Earth)

This is an opinion piece from a company that sells satellite-based solar-detection technology, so the proposed fix should be read with that in mind, but the underlying regulatory gap it describes is real and worth understanding on its own terms. From 27 August, plug-in solar becomes legal to self-install without a registered installer, and the compliance mechanism is connect first, then notify your network operator within 28 days under the existing G98 process. That is an honesty-system compliance model layered onto a category of installation that, by design, requires no professional involvement at any stage.

The Brazil comparison is doing the real work in this argument, and it is worth taking seriously independent of who is making it. Brazil now has an estimated 14 gigawatts of undeclared rooftop solar capacity, roughly a major hydroelectric dam's worth of generation that grid operators cannot see or plan around, and curtailment at Brazilian plants averaged around a quarter of potential output in June 2026, roughly double what it was a year earlier. That curtailment number is the concrete cost of invisible capacity: when operators can't see how much distributed generation exists, they manage the system more conservatively, and that conservatism shows up as wasted generation elsewhere on the network.

The UK is starting this process later than Brazil and with a lower per-unit cap (800 watts versus Brazil's typically larger rooftop systems), which should limit the scale of the problem in the near term. But the structural issue is the same: a self-install category with a self-reporting compliance mechanism will always undercount actual connected capacity by some margin, and the only real debate is how large that margin becomes as adoption scales. Kent's plug-in solar households legalising from 27 August are a genuinely tiny fraction of national capacity today, but the same 28-day notify window will apply to every household in the country choosing this route, and the aggregate visibility gap compounds with volume, not with any individual household's honesty.

For anyone installing plug-in solar under the new rules, the practical takeaway has nothing to do with satellite tracking and everything to do with the notify-within-28-days step itself: treat that registration as non-optional admin, not a formality to skip. The system working as intended depends entirely on households actually doing the self-reporting step, and this piece is a useful reminder that the entire regulatory model rests on that single, easily-forgotten action.

Read the original: Solar Power Portal (opinion, Maya Pindeus, Another Earth). Commentary is Sandwich Solar's own editorial view; the original reporting is credited to its publisher.

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