Connecting your panels to the grid in St Helens

Two routes

Most St Helens terraces and semis take systems small enough for the first route. A larger detached-house system, or a modest one with a battery, may need the second. The limit is about what the inverters can send out, not the panels' total rating, which is why an installer can sometimes keep a system on the simpler route with an inverter sized to suit.

Six St Helens systems and their route

Illustrations with panels of about 440 W; the route depends on the inverters, not the panels.

Microinverters count too

Shaded St Helens roofs often end up with microinverters or optimisers, as the guide to them explains, and the two are treated differently at the network. A microinverter is an inverter in its own right, so their ratings are added together: ten panels each with a 0.4 kW unit make 4 kW, over the single-phase limit for connecting first, even though no single unit is large. Optimisers sit behind each panel but feed one central inverter, so only that inverter's rating counts. Ask the installer which route the design will take before you agree to it.

Three phases

A few homes have a three-phase supply. Each phase can then take 16 amps on the connect-then-notify route, 11.04 kW across the three, as long as the inverters are spread between the phases. A large single-phase inverter on one phase is judged against that phase alone, so the installer needs to know which supply you have before choosing equipment.

When the system changes

The network needs to hear about the system as it stands now, not as it was first fitted. A battery added with its own inverter, panels on an outrigger roof with an inverter of their own, or a larger replacement inverter each changes the total. Once the new total passes the limit, the change waits for approval before it is switched on; below it, a fresh notification follows the work.

Checking your operator

If you live towards Newton-le-Willows or Haydock, ask the installer to confirm which network operator covers your street before it notifies anyone. We could not confirm the boundary from an official map, and a notification sent to the wrong company is a delay you do not need.

Time, money and the rest of the quote

An application costs little but can take weeks, so a quote should say whether one is needed and who makes it. A battery with its own inverter is a common reason for a modest system to need approval, which is worth weighing on batteries before you choose the equipment. Set the connection terms beside the price on prices, and the output beside the first-year sums on worth it.

The network operator

SP Energy Networks describes its SP Manweb network as serving Merseyside and North Wales. We could not confirm from an official licence map whether the eastern edge of the borough, around Newton-le-Willows and Haydock, falls in SP Manweb's area or Electricity North West's; the installer's notification goes to whichever serves your address.

Meters and export payments

To be paid for exports you need an MCS-certified installation and a meter that records exports, which in practice means a smart meter. Your supplier, or another supplier offering an export tariff, sets the rate. Apply once the installer has given you the MCS certificate.

What goes to the network

Whether it is a notification or an application, the installer tells the network operator where the system is, which inverters, optimisers, microinverters and battery it uses, with their ratings, and who fitted it; an application adds the design and any export limit. You may be asked to sign as the customer. Ask for a copy of what was sent and of any reply, and keep it with the certificates below.

Paperwork to keep

• The G98 notification, or the G99 approval with any export limit.
• The inverter's settings, including any export limit.
• The MCS certificate and the electrical installation certificate.
• Datasheets and warranties for panels, inverter, any optimisers and any battery.

Related pages

• Batteries
• Checking an installer
• Looking after panels
• Optimisers

References

1. SP Energy Networks: generation connections
2. SP Energy Networks letter to Ofgem (2020) on its SP Manweb area
3. NESO data portal: distribution network licence area boundaries
4. MCS MIS 3002 version 6.0: the solar PV installation standard
5. Ofgem: how export payments work for small generators