Battery retrofit

Add a battery to your existing solar panels

You already have solar panels. On a bright day you're sending electricity back to the grid for a few pence and buying it back in the evening for a lot more. A battery stores the daytime surplus so you can use it later. Pentland Renewables arranges retrofit batteries for existing solar systems across Edinburgh and the Lothians, and we'll tell you straight if your system or your usage doesn't make one worth it.

Ask about a battery retrofit

Is a retrofit battery worth it for you?

A battery usually makes most sense when:

You export a lot of your solar in the middle of the day
Your house uses most of its electricity in the evening and early morning
You're on, or could move to, a time-of-use tariff with cheaper overnight rates
You're planning a heat pump or an electric car, which will increase your evening and overnight use

It usually makes least sense when you're home all day and already use most of what your panels make, or when your solar system is very small.

We'll look at your generation and usage before recommending anything. If you have a smart meter, your supplier's app or your in-home display can show your import and export pattern.

AC-coupled or DC-coupled?

There are two common ways to add a battery to an existing system:

AC-coupled. The battery has its own inverter and connects into your home's AC wiring. It works with almost any existing solar system and leaves your current inverter alone. This is the most common retrofit option.
DC-coupled or hybrid. A hybrid inverter replaces your existing one and runs both the panels and the battery. It can be more efficient and makes sense if your current inverter is old or due for replacement anyway.

The right choice depends on your inverter's age, make and warranty, where kit can safely go, and your budget. We check all of this on the survey.

What we check on the survey

1. Your existing inverter. Make, model, age and condition.
2. Your consumer unit and wiring. Whether they can take the new connection safely.
3. Location. Garage, utility room, loft or outside wall. Batteries have rules on where they can go, and we follow the manufacturer's installation requirements.
4. Your usage. Generation, export and import pattern.
5. Grid notification. Adding a battery changes what's connected to the network. Depending on the combined size of your solar and battery, the connection may need notifying to, or approval from, SP Energy Networks. See our G98 and G99 guide.

VAT on retrofit batteries

Batteries installed in homes are currently zero-rated for VAT, including when they're retrofitted to an existing solar system, until 31 March 2027. From 1 April 2027 the rate is due to go back to 5%. Our VAT guide explains what's covered.

Home Energy Scotland's grant and loan no longer covers battery storage, so there's no Scottish grant for this at the moment.

Guide price: [PRICE: Iain to confirm]. We quote after the survey.

Will a battery affect my export payments?

If you're on the Smart Export Guarantee, adding a battery can change how much you export, and some suppliers have specific rules for systems with batteries. If you're on the old Feed-in Tariff, check your FIT terms before adding a battery, especially if your export is deemed rather than metered. We'll help you check before you commit.

Battery retrofit FAQs

Can a battery be added to any solar system?

Most, yes. An AC-coupled battery works with almost any existing system. Very old or unusual inverters may limit the options.

Will I have power in a power cut?

Not automatically. Many systems shut down in a power cut for safety. Some batteries offer backup power to selected circuits, but this needs extra equipment. Tell us if it matters to you.

How big a battery do I need?

It depends on how much surplus your panels make and how much you use in the evening. Bigger isn't always better. An oversized battery may rarely fill on a Scottish winter day.

Does adding a battery affect my Feed-in Tariff?

It can, especially if your export is deemed rather than metered. Check with your FIT supplier before fitting a battery. We can help you work out what to ask.

Is there VAT on a battery retrofit?

Batteries installed in homes are currently zero-rated until 31 March 2027, including retrofits to existing solar.

Do you cover my area?

We work with homes across Edinburgh, Midlothian, East Lothian and West Lothian.

Ask about a battery retrofit

Send us a photo of your inverter's label, a rough idea of your system size and your postcode. We'll tell you whether a battery is likely to be worth it and arrange a survey.

Ask about a battery retrofit