Connecting solar to the grid in Manchester: G98, G99 and SP Electricity North West

Who SP Electricity North West is, and who it is not

The grid company for every street in Manchester is SP Electricity North West. It owns the substations, underground cables and overhead lines that carry power around the region, and it writes the rules for connecting anything that generates electricity (enwl.co.uk). Older letters and websites may still call it plain Electricity North West.

It is not your energy supplier. The supplier sells you units, sends the bill and, if you sign up, pays for what you export. The network operator moves the power along the wires whoever you buy from. Changing supplier therefore never changes who handles a solar connection.

In practice you will hardly deal with the operator at all, because the installer handles the paperwork. The rules are still worth knowing. The connection route shapes three things in any quote: how large the system can be, how soon it can be switched on, and what documents you should hold at the end.

The local network is getting busier. On the way to its 2038 zero-carbon target, Manchester City Council expects the city to need almost 400 megawatts of solar and 54,000 heat pumps by 2030 (Manchester City Council, October 2025). Each of those systems joins the same cables, which is why the operator has to be told about every one.

G98: switch on, then notify

Most Manchester homes connect under G98, the engineering standard for small generators. It covers inverters up to 16 amps per phase. Most houses have a single-phase supply, so for them the ceiling is 3.68 kW. A home with a three-phase supply can go to 11.04 kW under the same rule (SP Electricity North West, micro-generation).

The limit applies to the inverter, the box that turns the panels' direct current into household power. It does not apply to the panels themselves. An installer can therefore put panels rated above 3.68 kW on the roof, pair them with an inverter at that rating and still use G98. The Energy Saving Trust's typical home system is 4.5 kWp (Energy Saving Trust), which is above the single-phase ceiling, so ask how your quote deals with it. On the brightest days an inverter at the limit holds its output there and lets the extra go.

The process is short. The installer fits and tests the system, switches it on, then notifies the operator. For a single home the notice is the G98 Form B. You do not have to fill it in, and you do not need to contact the operator yourself.

Three situations come up often in Manchester:

• Small rear slopes. On a terrace in Levenshulme or Gorton the usable roof is small, so the panels often sit comfortably behind a G98 inverter.
• Larger roofs. A big Victorian roof in Didsbury or Whalley Range may hold more panels than one 3.68 kW inverter can use well. The installer then weighs a larger inverter under G99 against a G98-sized inverter that trims the summer peaks.
• Three-phase supplies. Some larger houses have one. The 16-amp ceiling applies to each phase, which is how the three-phase figure reaches 11.04 kW.

G99: apply before connecting

G99 covers anything over the G98 limit. Here the installer applies to SP Electricity North West before the system is connected, and nothing is switched on until the operator agrees (SP Electricity North West, G99). The operator looks at whether the local network can take the extra power, and it may attach conditions to its answer.

For Manchester homes the usual reason for G99 is a battery. A battery with its own inverter adds to the total rating at the property. Solar that fits within G98 on its own can tip over the limit once a battery inverter joins it, and the combined system then needs a G99 application. A single hybrid inverter that runs both panels and battery, rated at 3.68 kW or less, keeps everything within G98.

The trap is adding a battery later. If the panels went in under G98 and a different firm adds a battery some years on, the new total may need a G99 application that nobody planned for. Mention any battery plans at the start, even vague ones. The guide to batteries in Manchester covers sizes and what they cost.

G99 adds time, and sometimes cost, to a job. How long depends on the operator's workload and on what its study finds, so no installer can promise a date at quote stage. A quote that assumes G99 should say so. It should also say who pays if the operator asks for work on the network. That line is worth comparing across quotes, along with the other checks in choosing an installer in Manchester.

Export limitation in plain terms

Export limitation is a cap on how much power a home can push out to the network at any moment. It is a setting in the inverter, or a separate controller with its own sensor. It does not limit what the panels make or what the house uses. Anything above the cap that the house cannot use is either stored in a battery or held back by the inverter.

It matters because it can make a larger system acceptable to the network. Rather than reinforce a cable or a substation, the operator can accept a system on condition that exports never pass an agreed level. The details sit within the G99 process on the operator's generation connections page.

There is a trade-off. A cap reduces what goes out to the grid on the sunniest days, and so reduces what an export tariff pays for. A household that uses most of its power in the evening loses more exported kWh to a cap than one with a battery and high daytime use. The guide to export payments shows how much a typical Manchester roof is likely to send out over a year.

If an installer mentions export limitation, ask three things. At what level will the cap be set? Is it a condition from the operator, or the installer's own choice? And how many kWh a year is it expected to hold back on your roof?

Where the connection fits in the job

For a typical Manchester house the order of work runs like this:

1. A survey of the roof, the shading and the electrics, including the supply and the main fuse.
2. A design that fixes the panel layout, the inverter rating and therefore the route: G98 or G99.
3. For G99 only, the application and a wait for the operator's answer.
4. Scaffolding, plus a council permit wherever it stands on the public pavement.
5. Fitting, testing and switching on.
6. For G98, the notification to the operator after switch-on.
7. Certificates handed over, then an export tariff arranged with a supplier.

The order matters most under G99. Scaffolding should not go up before the operator has agreed, and you should not hand over a large stage payment for fitting before then either. Ask the installer to confirm that sequence in writing, alongside the start date.

What to ask the installer, and what to keep

Because you will rarely speak to the operator, every question goes to the installer. Ask before you sign, and get the answers in writing.

1. Does this quote assume G98 or G99, and why?
2. What is the inverter rated at, and what is the total panel rating in kWp?
3. Is my supply single-phase or three-phase, and is the main fuse adequate?
4. If I add a battery later, will the total still fit within G98?
5. Will the system be export-limited, and to what level?
6. Who sends the notification or application, and when do I get a copy?
7. If the operator wants network work, who pays and how long might it add?

After the job, keep one folder holding the commissioning record, the MCS certificate, the electrician's installation certificate, and the G98 notification or the G99 agreement. Export tariffs need the MCS certificate, and a buyer's solicitor may ask for the rest when you sell. Price is a separate check: the North West cost figures show what homes in the region actually paid per kW.

Flats are a different case. In a block, the roof and the incoming supply normally belong to the building owner, and a shared system raises connection questions that a single house never meets. Purpose-built flats house 28.1% of the city's households (ONS Census 2021), so the guide for flats starts with who decides.