Connecting solar panels to the grid in Northwich

Supplier and network operator are different companies

Two companies stand between your home and the wider electricity system, and they are easily confused. Your supplier is the company that sells you electricity, sends the bills and, if you choose it, pays you an export tariff. You can switch supplier whenever your contract allows. Your distribution network operator, or DNO, owns and runs the cables, substations and poles that carry electricity along your street to the meter position. You cannot choose it: it is fixed by where you live, and it stays the same when you change supplier.

For solar, the network operator is the one that matters at connection. It needs to know what generating equipment is attached to its network, because a lot of solar on one street changes how the local cables behave on a sunny afternoon. The supplier comes into the story later, for the export tariff, which is explained in export and self-use.

Finding the operator for a Northwich address

This guide does not tell you which company runs the network at your address, and a general description of regions is not a safe substitute. Use the Energy Networks Association’s postcode search, which gives the operator for any postcode you enter. The reason for caution is that operator areas do not follow county boundaries neatly. SP Energy Networks, for instance, describes its Manweb area as covering Merseyside, North Wales and parts of Cheshire. “Parts of Cheshire” is exactly the kind of phrase that makes a postcode check worth the minute it takes.

The installer will normally establish the operator during the survey, and the notification or application goes to that company. Knowing it yourself is still useful if you ever need to contact the operator about a power cut, a change to your supply or a question about the paperwork.

G98: the route for most home systems

G98 is an Engineering Recommendation, the industry standard for small generators connected to the low-voltage network that serves homes. Its limit is a current of 16 amps per phase. On a single-phase supply, which many homes have, that equals 3.68 kW of inverter output. Within that limit, connection is a matter of notification rather than permission:

1. The installer fits and commissions the system using an inverter type-tested for G98.
2. Within 28 days of commissioning, the installer notifies the network operator.
3. The operator records the system. No approval is needed before it is switched on.

The notification is the installer’s job, but the system is yours, so ask for a copy of what was sent. It is one of the documents a future buyer’s solicitor may want to see.

G99: apply first

Above the G98 limit, notification gives way to application. Under G99, the installer applies to the network operator before connecting, and the system must not be connected until the operator has replied. The operator considers what the local network can take, and may accept the system as proposed or attach conditions to it.

Three situations commonly push a home system into G99:

• a larger array with an inverter rated above 3.68 kW on a single-phase supply;
• solar plus a battery, where the combined inverter output exceeds the limit (see batteries);
• adding panels or a battery to an existing system, so that the total rises past the limit.

G99 adds time. Ask at the quote stage which route your design falls under, who will make the application, and whether the timetable allows for waiting on the reply. A firm that proposes to connect a G99 system first and apply afterwards is cutting a corner that matters.

Single-phase or three-phase?

The limit is set per phase. A single-phase supply brings one live conductor into the house; a three-phase supply brings three. Many homes are single-phase, and the installer can confirm which you have by looking at the main fuse and the meter. On a three-phase supply the 16 amp limit applies to each phase, which leaves room for a larger system within G98 if it is balanced across the phases. Changing a single-phase supply to three-phase is a separate request to the network operator and is not something to assume will be quick.

Panel rating and inverter rating

The limits concern inverter output, not the combined rating of the panels. Panels are rated in kWp, their output under standard test conditions, and on a Northwich roof they seldom reach that peak in ordinary use. It is therefore normal for the panel rating of an array to be a little above the inverter’s output rating. A quote might pair panels rated above 3.68 kWp in total with an inverter limited to 3.68 kW, keeping the system inside G98. Ask how the design was arrived at and what the inverter rating is, because that is the number the network operator looks at.

Why the inverter switches off in a power cut

Part of what the connection standards require is protection: the inverter must disconnect if the network goes down. When a fault cuts power to your street, people may be working on the cables, and a house that kept pushing solar electricity onto a line believed to be dead would put them at risk. So a standard grid-connected system stops producing during a power cut, even on a bright day. Systems that can keep chosen circuits running in an outage use extra equipment that isolates the house from the network first, and that has to be designed in from the start.

On commissioning day

At commissioning the installer tests the system, checks the inverter’s protection settings and confirms the inverter output matches the design that was notified or approved. Ask for the commissioning record along with the certificates. If the installer later changes anything that affects output, such as swapping the inverter or adding a battery, the operator may need to hear about it again.

Who does what

Meters and the export tariff

Connection to the network and payment for exports are separate matters. Once the system is connected, you need a meter that can record what you export and an export tariff from a supplier under the SEG, Ofgem’s export tariff rules. The supplier will ask for the MCS certificate, and the MCS installer directory is where to confirm the firm was certified to issue one.

A busy local network

Every notification and application adds to the operator’s picture of its network. Government figures show 11,740 solar PV sites in Cheshire West and Chester at the end of 2025, up from 5,759 at the end of 2019 (DESNZ). Those counts include business and other non-domestic sites as well as homes, and each was connected under the rules that applied at the time. The trend is examined in solar take-up locally.

Questions for the installer about connection

1. Which network operator serves my address?
2. Does my design fall under G98 or G99, and why?
3. What is the inverter’s rated output, and is my supply single-phase or three-phase?
4. If G99 applies, when will you apply, and will you wait for the reply before connecting?
5. Will you give me a copy of the notification or the approval?

Those copies belong with the rest of your solar paperwork; why they matter when a house changes hands is explained in buying a Northwich home with solar. The other checks worth making on a firm are in choosing an installer.