Retrofit solar battery Add a battery to the panels you already have

Can I add a battery to my existing solar system?

Almost always, yes. Most existing solar PV systems can take a battery. What changes is how it connects, which depends mainly on your current inverter, and whether any other work is needed first. Adding battery storage lets you store electricity your panels generate in the day and use it in the evening, instead of buying it from the grid. You use more of your own solar electricity, which can bring your bills down, depending on when you use it.

Look at your solar generation and export first

Open your solar app, or look at your export meter, and check how much of your solar generation you send to the grid. A battery tends to pay its way when:

• you export a lot of excess solar power on sunny days because nobody's home
• you buy most of your electricity in the evening, after the panels have stopped
• you're on one of the smart tariffs with cheap overnight electricity, or would switch to one
• you have an electric car, or are getting a heat pump

If you're home all day and already use most of what the panels produce, a battery adds less. We'll tell you if that's you.

System design: what we check

Every battery retrofit starts with a free consultation about your current system, and a technical survey once you've signed. Between them, we check:

1. Your inverter. Make, model, age and condition. This decides AC or DC coupling.
2. Your paperwork. Your MCS certificate and any Feed-in Tariff or export tariff details. If you've lost them, we can still work from the system itself.
3. Where the battery can go. The fire safety standard for home batteries, PAS 63100, prefers outdoors and rules out lofts, bedrooms and escape routes such as landings and stairs. A garage, utility room or outside wall is usual.
4. Your consumer unit and meters. Room for the new circuit, and whether you have a smart meter that records exports. To be paid under the Smart Export Guarantee, you need a meter that can take half-hourly export readings.
5. The network connection. A battery counts as generation. If your panels and battery together exceed 3.68 kW per phase, we apply to the network operator for approval before fitting, often through a fast-track process.

Solar panels fitted by someone else?

That's fine, and common. Plenty of people who had solar panels installed years ago now want a battery, and the original company may have closed or stopped doing batteries.

We don't need the original installer's involvement. We check the system, fit the battery to the same standards as our own installs, notify the network operator and give you your own MCS certificate for the battery.

Installing battery storage on an existing system

A solar battery retrofit doesn't involve the roof, so there's normally no scaffolding. Our approved electrician fits the battery, and the hybrid inverter if you're having one, connects it to your consumer unit on its own circuit with isolator switches, and tests everything. We then set up the app and the battery's smart controls, such as charging on a cheap overnight rate, and show you how they work. From then on, the stored energy can cover some of your evening use and cut your grid imports.

Afterwards we notify your network operator (or apply first, if the system goes over 3.68 kW per phase), register the battery for its MCS certificate and email your handover pack within 7 working days.