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DNO limits explained: export vs generation limits

Short answer

An export limit caps net power to the grid at the meter, enforced by a G100 scheme with a grid CT. A generation limit caps the inverters' total AC output (Registered Capacity) in protected settings. DNOs may impose either. With a 5 kW export cap, an 11 kW inverter can still supply the home at up to 11 kW.

Last checked 24 September 2026 · 3 sources

What should I know before deciding?

Export limit breaches are prevented by G100 fail-safe on CT loss. Generation limit reduces what G98/G99 counts; changing it needs DNO notification (G99 20.3.2). Some installer sites wrongly define 'generation limit' as array size.

Does a battery need G98 or G99?

Yes, one of them. G98 and G99 define generation to include electricity storage that can export, so a battery inverter counts. If everything on site, solar plus battery inverters, stays within 16 A per phase (3.68 kW single-phase), G98 connect-and-notify applies. Above that, use G99, via an SGI fast-track route with G100 export limitation or a standard application.

Registered Capacity of an inverter = lesser of inverter rating or energy source rating; software limits allowed if not customer-accessible. Adding an AC battery to existing 3.68 kW PV usually takes the site over 16 A, triggering G99 (SGI-2 with 16 A export limit is typical).

Can my battery inverter be turned up later?

Sometimes. Some inverters are software-configurable - Powerwall 3's UK output can be set from 3.68 to 11.04 kW. G99 lets a unit be limited to 16 A for a simpler notification, but raising the limit later needs a new application to the DNO. Many inverters have a fixed rating.

G99 SGI-1 (c): increasing output beyond condition requires Form A1-1 or A1-2.

Can an inverter's rating be raised in software later?

Sometimes. G98 and G99 let manufacturers limit Registered Capacity in software if the customer cannot change it. Powerwall 3 is configurable from 3.68 to 11.04 kW. But raising it later changes Registered Capacity: G99 requires the DNO to be notified before the change, and going above 16 A per phase needs a new G99 application.

A 20% or greater capacity increase counts as significant modification (G99 20.3.6). Record the configured rating and firmware at commissioning. Hardware that is physically 3.68 kW cannot be raised.

What to do next

Ask the installer to show the proposed location, DNO route, backup arrangement and commissioning documents before work starts.

Sources

Last checked: 24 September 2026