Connecting solar panels to the grid on the Wirral

Who runs the wires

There are two different companies in your electricity bill. Your supplier sells you electricity and pays you for exports. The distribution network operator owns and runs the poles, cables and substations that carry it. On the Wirral that is SP Energy Networks, through the licensee SP Manweb plc, whose "Manweb" area covers Merseyside, North Wales and parts of Cheshire. SP Energy Networks lists offices and depots on the Wirral itself. You do not choose it and you do not pay it directly; its charges are part of the standing charge and unit rate on your bill.

When you add solar panels, you add a small generator to that network. The network operator needs to know where generators are and how big they are so that it can keep voltages within limits on your street. That is all the connection rules are for.

G98: connect and notify

SP Energy Networks explains that G98 applies to small generators of under 3.68 kW per phase, and G99 to anything larger. Most Wirral homes have a single-phase supply, so the G98 limit is set by the inverter: if the inverter (or inverters) can export no more than 3.68 kW, the installer can connect the system and then notify SP Energy Networks. You do not need to wait for permission.

This is why many systems of around 4 kW of panels use an inverter rated at 3.6 or 3.68 kW. The panels can still produce more than the inverter's rating on a bright day, but only briefly, and the loss is small. On the Wirral, where the brightest hours are in late spring and summer, an inverter a little smaller than the panel array is normal practice.

Thresholds as stated by SP Energy Networks, read 3 November 2026.

G99: apply first

If the inverters can push more than 3.68 kW per phase, the installer must apply to SP Energy Networks under G99 and wait for approval before connecting. That happens with:

• larger arrays, such as 5 or 6 kW on a detached house with an inverter to match;
• a battery with its own inverter added to an existing solar system, if the two together could export more than the limit;
• systems on a three-phase supply above the per-phase limits.

The network operator may approve the connection as it is, ask for an export limit (a setting that caps how much the system sends to the grid at once), or, rarely, need work on the local network first. A G99 application adds time, so ask at the quoting stage whether your system will need one and who pays for any extra.

Batteries count too

A home battery connects through an inverter and, for the network operator, counts as generation when it discharges. SP Energy Networks has a separate page on energy storage. A hybrid inverter that serves both panels and battery keeps the total within one rating, which can keep the whole system under G98. A battery added later with a second inverter may tip it into G99. See adding a battery.

Meters and getting paid for exports

To be paid for what you export under the Smart Export Guarantee you need two things: an MCS certificate for the installation, and a meter that records exports separately. A smart meter does both import and export. If you have an older meter, ask your supplier for a smart meter before the installation, or at least before you apply for an export tariff. Your installer will often fit a separate generation meter too, which records everything the panels make; that one is for your own information and your warranty.

What the installer should hand over

• confirmation that SP Energy Networks has been notified under G98, or the G99 approval;
• the inverter's settings, including any export limit;
• the MCS certificate and the electrical installation certificate;
• a labelled isolator for the panels and one for any battery, so that an electrician or the fire service can switch the system off safely.

Keep these with the rest of the paperwork described in the guide to choosing an installer. You will need them to apply for an export tariff and if you ever sell the house.

Power cuts

A normal grid-connected system switches off when the grid goes down. This is a safety rule: the panels must not feed power into cables that engineers think are dead. If you want power in a cut, you need a battery and inverter with a backup or emergency power function, which is a separate feature to ask about and usually covers only some circuits.