The short answer
Find the network operator for your address with the ENA postcode search. On a single-phase supply, systems up to 16 A per phase, or 3.68 kW, are connected first and notified within 28 days under G98. Larger systems, including panels plus a battery over that limit, need approval before installation under G99. The firm normally handles both.
Who is involved
Three parties sit behind every solar connection. The supplier sells you electricity, sends the bill and may pay you for exports. The network operator owns and runs the local cables, transformers and substations, whichever supplier you use. The installer fits the system and deals with the operator on your behalf. This guide does not name the operator for Congleton; use the Energy Networks Association’s postcode search to find the one that serves your address.
The operator needs to know about generation on its network because power can now flow in both directions along cables that were designed to carry it one way. Many small systems on one street can change voltages and loads, so the operator keeps a record of each one and, above a certain size, checks the design before it is connected.
The two procedures
| Situation | Procedure | Timing |
|---|---|---|
| Panels with an inverter up to 3.68 kW, single-phase supply | G98 | Connect, then notify within 28 days |
| Panels plus battery, combined output up to 3.68 kW | G98 | Connect, then notify within 28 days |
| Panels or panels plus battery above 3.68 kW, single-phase | G99 | Apply and wait for approval before installing |
| Larger array with output limited to 3.68 kW by the equipment | Depends on the operator’s view of the limit | Ask the firm to confirm before signing |
| A second system added to an existing one | Based on the combined total | Count both systems together |
G98 covers small generators: up to 16 A per phase, which on the single-phase supply most homes have is 3.68 kW. The system is installed and connected first, and the installer notifies the operator within 28 days of commissioning. No approval is needed in advance.
G99 covers anything larger. The installer submits an application with details of the equipment and the connection, the operator assesses it, and work must not be connected until the operator has given approval. The assessment can take some weeks, and on a crowded part of the network it may come back with conditions.
What counts towards the limit
The figure that matters is the output of the inverter or inverters, not the total rating of the panels. A 4.4 kWp array on a 3.68 kW inverter can still fall under G98, because the inverter limits what reaches the house wiring. Panels rarely produce their full rated output in Congleton’s conditions anyway: an unshaded south roof averages about 909 kWh per kWp a year in the PVGIS runs for this guide.
A battery’s inverter is generation too. If the battery can export while the panels are also producing, the two outputs are added together for these purposes. That is why panels plus a battery on a single-phase supply often cross into G99 even when each on its own would not. Batteries explains the other trade-offs of adding storage.
Systems added later are counted with the existing ones. If you already have panels and want more, or a battery, the new equipment is assessed on the combined total.
Export limits
Equipment can be set to cap what flows back to the grid, so that a larger array or a battery behaves like a smaller system as far as the network is concerned. Whether such a limit brings a system within the simpler route, or forms a condition of a G99 approval, is for the operator to decide under its rules. Ask the firm to confirm the position in writing before you sign. A limit means that on bright summer days, output above what the house can use and the limit allows is lost, so ask how much that is likely to be.
Larger arrays come up most on detached houses with several slopes: see detached homes. East and west arrays rarely reach their full rating at once, which can make a smaller inverter sensible: see east and west roofs.
Three-phase supplies
Some larger houses and some converted industrial buildings have a three-phase supply. The 16 A threshold then applies to each phase, which allows a larger system under the simpler procedure if the generation is spread across the phases. Check what supply the building has before assuming either way; it is usually shown on the main fuse or meter, and the firm should confirm it on the survey. For blocks of flats, each flat’s supply and the landlord’s supply are separate connections: see mill conversions and flats.
The meter and export payments
Network paperwork and export payments are separate. The operator needs to know the system exists; the supplier paying for exports needs a meter that records them, usually a smart meter, and the system’s MCS certificate. Larger suppliers have to offer an export tariff under the SEG (Ofgem). The household registers for that tariff itself, after the system is running: export and self-use covers the details.
Fitting the connection into an older house
The physical connection is usually modest: a cable from the inverter to the consumer unit, a dedicated circuit protected in the unit, and isolating switches so the system can be made safe for maintenance. Warning labels go at the meter and the consumer unit so that anyone working on the supply knows there is a second source of power. In older Congleton houses the consumer unit is sometimes old enough to need replacing before a new circuit can be added, and the earthing may need improving. A good survey spots both, and the quote should say whether either is included.
Where the meter sits in an outside box or a cellar, the route from the inverter to the meter and consumer unit may be long or awkward. In a listed building, drilling for that route is a change to the historic fabric and belongs in the consent application.
How long the steps take
For a G98 system the network side adds no waiting: the work is done, the system switched on and the notification sent within the following four weeks. For a G99 system, build the operator’s assessment into the timetable before agreeing an installation date, because the firm should not connect until approval arrives. Applications that need a closer look at the local network take longer. If a firm proposes to fit a G99 system and connect it before approval, that is a reason to look elsewhere.
A system that was never notified
Occasionally a household finds that an older system, or one fitted by a firm that has since closed, was never reported to the operator. The fix is to have a certified firm inspect the system and submit the notification now, with whatever certificates exist. It is better done before a sale, when a buyer’s solicitor is likely to ask, than after.
What to ask the firm
- Is this system G98 or G99, and on what figures?
- If G99, when will you apply, and will any work start before approval?
- If an export limit is proposed, how much summer output will it cost?
- Does adding a battery now or later change the procedure?
- Will I receive copies of the notification or application, and the operator’s reply?
A firm certified by MCS will know these procedures well; confirm its certification on the MCS search. Choosing an installer lists the other checks.
Keeping the record
Once the system is connected, the notification or approval belongs with the household’s other papers: the MCS certificate, the electrical certificate and the warranties. A buyer’s solicitor may ask for it, and a later firm adding a battery will need it. If you are buying a house that already has panels, ask the seller for it: buying a home with solar explains what else to request. Questions about a particular property can go through the question form, and brief answers on related topics are on the FAQs page.