Every solar panel system and home battery in Great Britain works connected to the grid, so your local network operator (the DNO, the company that runs the cables in your street) has to know about it. The rules come from the Energy Networks Association in two documents, G98 and G99. Which one applies decides whether your installer can fit the system and tell the DNO afterwards, or has to apply and wait for an answer first.
What decides it: the size of what’s installed
The test is the total capacity of the equipment that can feed power into your home’s wiring: the solar inverter and the battery inverter, added together. It isn’t how much you export to the grid. A battery counts in the same way as solar panels, because it can push power out too.
Capacity is measured in amps per phase. Most homes have a single-phase supply, where 16A is 3.68kW. Some larger homes have a three-phase supply, where 16A on each phase is 11.04kW in total.
G98: fit it, then tell the DNO
G98 covers small systems: no more than 16A per phase in total (3.68kW on a single-phase home), using equipment that is fully type tested, meaning the manufacturer has proved it meets the standard. The installer fits and commissions the system, then notifies the DNO within 28 days.
A modest solar system on its own often fits. Add a battery with its own inverter and the total usually goes over 16A, which takes you into G99. One exception: several G98 systems planned close together, such as on a new estate, need the DNO’s agreement first.
G99: the route most solar and battery homes take
G99 covers anything bigger than G98. For homes, it has three simpler routes, called Small Generation Installation procedures. Which one applies depends on the size of each inverter, the total, and whether an export limit is fitted.
- Set to G98 size. If bigger inverters are set so the whole system can produce no more than 16A per phase, the installer can still fit first and notify the DNO afterwards.
- Export limited to 16A. Each unit set to no more than 16A, a total of up to 32A per phase, and an approved export limiter holding what goes to the grid to 16A. The installer applies first, and the DNO answers within 10 working days.
- Larger home systems. Units up to 32A each, a total under 60A per phase, and export limited to 32A (no limiter is needed if the total is 32A or less). The installer applies first. Within 10 working days the DNO says whether it needs to study your local network before agreeing.
- Anything bigger, including many commercial systems, goes through the DNO’s standard G99 application. That takes longer and can include a quote for work on the network.
What an export limit means
An export limit caps how much power can leave your home for the grid. Your panels still power your home and charge the battery first. An approved limiter watches your supply and turns output down within seconds if export goes over the limit. On the sunniest afternoons, when your home and battery can’t take any more, the panels are turned down rather than exporting, which can trim your export payments.
An export limit doesn’t turn a large system into a G98 one. It’s what lets a larger system use the quicker G99 routes.
What it means for your timeline
On the quicker G99 routes, the DNO replies within 10 working days, and the planned connection date on the application has to fall between 10 working days and 3 months after it’s sent. We apply as soon as your design is agreed, so the answer is usually back well before your installation date. If the DNO needs to study the local network, it can take longer, and we’ll tell you straight away.
Whichever route applies, we confirm the finished system to the DNO within 28 days of commissioning.
What Powergy handles
- Working out the right route from your actual design, before you commit
- Preparing and sending the notification or application, with the equipment’s test certificates
- Fitting and setting up any export limiter the route needs
- Telling you if the DNO sets a limit, and what it means for your savings
- Confirming the finished system to the DNO and registering it with MCS, which you need for export payments
An export limit changes the economics of your system, and you deserve to know that before you sign, not after. It’s part of every Powergy proposal as standard. Curious what your grid connection allows? Ask us, it costs nothing to find out.
This guide is general information, not advice for your specific property. It follows the Energy Networks Association's G98 and G99, Issue 2 (March 2025), which apply in England, Scotland and Wales; Northern Ireland has its own versions. Your Powergy designer confirms the route for your system.