G99 application support for solar PV, EV charging & battery projects

A G99 application is the formal DNO process used where generation or storage equipment connects in parallel with the distribution network and falls outside G98 limits. In practice, this usually means systems above 16A per phase, or projects that need a more detailed DNO assessment before installation or commissioning.

G98 generally applies to fully type-tested microgeneration up to and including 16A per phase — approximately 3.68kW on single-phase or 11.04kW on three-phase at nominal voltage. G99 applies above that threshold, or where the installation does not meet the relevant G98 conditions.

At nominal voltage, 16A per phase corresponds to approximately 3.68kW on a single-phase supply and 11.04kW on a three-phase supply. Anything above those limits should normally be considered under G99, although the correct route still depends on the full site arrangement and equipment details.

For many lower-voltage projects, DNO assessment is often planned around a 45 working day response period once the application is complete. Higher-voltage or more complex connections can be longer, commonly around 65 working days or more depending on scope, reinforcement, interactive queue position and DNO requirements.

If the project requires G99 approval, it should not normally be commissioned in parallel with the network until the DNO has approved the connection arrangement. Starting too early can create compliance, programme and commercial issues if the DNO later requires export limitation, reinforcement or a different connection arrangement.

Typical inputs include site address, MPAN, proposed generation/storage capacity, inverter details, single line diagram, import/export assumptions, protection information, equipment certificates and any export limitation arrangement. Missing or inconsistent information is a common cause of delay.

G100 export limitation is used where installed generation or storage capacity is higher than the agreed export limit. It is common on commercial solar PV and battery projects where the site wants a larger installed system but the DNO will only allow a lower maximum export level.

EV chargers are demand/load, so they do not normally require G99 by themselves. They may require DNO notification or approval under EV/heat pump connection processes. If EV charging is combined with solar PV, battery storage or export-capable generation, G99 and/or G100 may become relevant.

The most common causes are incomplete or inconsistent technical information — missing inverter certificates, incorrect MPAN, mismatched single line diagrams, or export assumptions that don’t align with the proposed equipment.

On more complex sites, failure to identify export limitation requirements early, or submitting without understanding the DNO’s local network constraints, can result in significant delays or unexpected reinforcement costs. Getting the application right first time is almost always faster and cheaper than correcting a rejected submission.

Speak before pricing the job, agreeing programme dates, promising export capacity, ordering major equipment or accepting a DNO position you are not comfortable with. Grid issues are usually easier to deal with before the commercial offer to the customer is locked down.