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Connecting solar and batteries: notify after, or ask first

There is one threshold that decides whether a solar or battery installation is a day's work or a job with a waiting period in the middle of it, and it is worth knowing before you give someone a date.

The threshold

Small installations are covered by ENA Engineering Recommendation G98: up to 16 A per phase, and the network operator can be notified after connection, within 28 days. Anything above that falls under G99, and there permission has to be obtained before the work. Source: Energy Networks Association, consulted 23 August 2026.

That is the whole rule in two sentences, and it has more effect on scheduling than anything else in a renewables job.

Why it belongs in the quote, not the install

A G99 application takes time that is not yours to control. If that is discovered when the scaffold is booked, you have a customer with a date you cannot keep and an install crew with a gap. Checking which side of 16 A per phase a design falls on is a survey question, and the answer belongs on the quote alongside a realistic date rather than an optimistic one.

Design decisions move the line

The threshold is about what can be exported, which means the inverter and its settings matter as much as the panel count. A system that could be limited to sit under the threshold is a different job — commercially as well as technically — from one that cannot. That is a conversation worth having with the customer at design stage, because they are the one who ends up waiting.

Fourteen licence areas, six groups

Britain has fourteen distribution licence areas across six DNO groups, but they share a common framework in G98 and G99. That makes this simpler than it looks from the outside and simpler than the equivalent in some other countries: the threshold is national, so a rule of thumb that works in Manchester works in Exeter.

Keep the paperwork with the property

The notification, the reference, the approval and the commissioning records all belong to the address, not to a folder organised by month. Three years later — at a sale, at an insurance claim, or when the customer adds a battery to an existing array — somebody will need them, and the address is the only thing that will still be true. See handover packs.

And the VAT

Solar and battery installation in homes is zero rated for VAT until 31 March 2027, then 5% — see VAT on energy-saving materials. On a system quoted now for installation next spring, that date is close enough to matter.