Grid Connection for Solar and EV Charging: G98, G99 and the DNO
A solar EV charging project asks the distribution network operator (DNO) two separate questions: can the site export generation, and can it import more power for the chargers? Generation follows the engineering recommendations G98 and G99; chargers follow the DNO's demand-connection process. Getting both into one plan early is what keeps the grid off a project's critical path.
Two processes, not one
| Solar array, battery, V2G charger (generation) | Ordinary EV chargers (demand) | |
|---|---|---|
| Rules | ENA Engineering Recommendation G98 or G99 | The DNO's process for new chargepoint and heat-pump connections, coordinated through the Energy Networks Association |
| Small installations | G98: up to 16 A per phase (3.68 kW single-phase) — connect, then notify the DNO | Smaller installations are typically notified to the DNO after installation |
| Larger installations | G99: anything above 16 A per phase — apply and receive the DNO's agreement before connecting | Larger loads, or any that need more capacity than the site's supply provides, are applied for before connection |
| What decides it | Inverter capacity per phase and how much you want to export | The site's agreed supply capacity and how the chargers are controlled |
Almost every commercial array is above the G98 limit, so it needs a G99 application. A single-phase 4 kW inverter already delivers about 17.4 A at 230 V — just over 16 A — which is why "small" in G98 means domestic-scale. A battery that can discharge to the site, and a vehicle-to-grid charger that can send power back, are generating units too, and fall under the same G98/G99 rules as the panels.
The solar side: G99 and export limits
A G99 application describes the inverters, protection settings and the maximum the site will export. The DNO checks whether the local network can accept it; where it cannot take full export, it may offer a connection with a lower export limit. An export limitation scheme — a meter and controller that throttle the inverters when export approaches the limit, designed to ENA Engineering Recommendation G100 — lets a site install more panels than its export allowance, provided most of the output is used on site.
That is where EV charging changes the arithmetic. Chargers that follow the solar surplus raise on-site use, so a site with a tight export limit can still justify a larger array. The load management guide covers the controller side; this is the reason to design the two systems together rather than in sequence.
The charging side: supply capacity
For import, the question is whether the new charging load fits inside the site's supply capacity. Half-hourly-metered business sites have an agreed capacity in their connection agreement and on their bills; exceeding it can bring excess-capacity charges and, eventually, a requirement to upgrade. Three ways to fit chargers in, in order of cost:
- Measure first. Twelve months of half-hourly data show the real peak. Many sites have more headroom at the times vehicles charge than their nameplate loads suggest.
- Dynamic load management. A controller shares the available capacity across sockets and holds total demand under the limit. On most workplace sites this is what decides how many sockets the existing supply can carry.
- More capacity. If the site still needs more, the DNO quotes for the work. Costs and lead times are site-specific; ask for the quote early, because it can decide whether the project is viable.
Rules for new buildings sit alongside this. Under Approved Document S, new non-residential buildings and major renovations with more than ten parking spaces need at least one chargepoint and cable routes for one space in five, with an exemption where the grid connection cost would exceed £3,600 per chargepoint.
Sequencing a combined application
- Collect the data: the supply's agreed capacity, twelve months of half-hourly consumption, the planned array size and the charger schedule.
- Model the combined profile: building load plus managed charging against generation, half-hour by half-hour. This shows the peak import with load management, and how much would be exported.
- Submit the G99 application with a realistic export figure — using an export limit if the network is constrained — and tell the DNO about the chargers through its demand process, or apply for more capacity if the model shows you need it.
- Order hardware once the DNO has responded. Inverters, protection settings and the export-limitation scheme must match what the DNO agreed.
- Commission and notify: the installer completes the DNO's commissioning paperwork for the generation and records the chargers.
The grid work is usually the longest-lead item, so it should start before the vehicles arrive, before the WCS voucher is applied for, and well before the 31 March 2027 deadlines for the WCS and the chargepoint first-year allowance. For the cost side see what solar EV charging costs; for how the whole system works, the main solar + EV charging guide.
Batteries and vehicle-to-grid
A battery lets a site store midday solar for evening or overnight charging and can shave import peaks, but because it can discharge it is a generating unit under G98/G99, and its export capability has to be declared. Bidirectional vehicle-to-grid chargers are treated the same way. The vehicle-to-grid page covers where V2G stands commercially in 2026; for grid purposes the point is simply to include any storage or V2G in the G99 application from the start rather than adding it later.
Grid connection questions
Does commercial solar need a G99 application?
Almost always. G98 covers installations up to 16 A per phase (3.68 kW single-phase); anything larger needs G99, which means applying to the DNO and receiving agreement before connecting.
Do EV chargers need a G99 application?
Ordinary chargers do not: they are demand, handled through the DNO's process for new chargepoints. A vehicle-to-grid charger or a battery that can export is a generating unit and does fall under G98 or G99.
Can load management avoid a supply upgrade?
Often. A dynamic load management controller shares the site's available capacity across the sockets and keeps total demand under the agreed limit, so more sockets fit on the existing supply.
What is an export limitation scheme?
A meter and controller, designed to ENA Engineering Recommendation G100, that throttle the inverters when export approaches an agreed limit. It lets a site install more solar than the network will accept as export, provided most output is used on site.
How long does a G99 application take?
It depends on the DNO, the size of the system and the local network. Start the grid conversation before ordering hardware or applying for the Workplace Charging Scheme voucher.
Sources
- Energy Networks Association — Engineering Recommendations G98 (16 A per phase), G99 and G100 (export limitation schemes).
- Energy Networks Association — process for connecting EV chargepoints and heat pumps.
- Approved Document S — Infrastructure for charging electric vehicles (England).
- GOV.UK Find a Grant — Workplace Charging Scheme (closing date 31 March 2027).
Checked 27 September 2026. DNO processes differ in detail between regions; your DNO's own guidance is the document of record. The depot charger grant listing does not say whether grid connection is an eligible cost, so price the grid work separately.
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