How to add battery storage to a Feed-In Tariff solar system
A simple guide to adding a battery to your FIT solar system – without putting your payments at risk.
If you’ve got solar panels on the Feed-In Tariff (FIT) scheme, adding a battery is one of the best ways to get more from the electricity you already generate.
The process is usually straightforward, with just a few additional requirements to make sure your payments continue as expected. A good battery installer will check your existing system, recommend a suitable battery, support you through the required paperwork and make sure everything is set up correctly.
This guide explains how battery storage works with a FIT solar system, how to ensure your payments aren’t put at risk, and how to choose the right battery for your home.
Written by Ben Watts, Solar Technical Specialist, who has been helping homeowners make the most of solar and battery technology for more than three years at Good Energy. Ben is passionate about supporting the UK’s transition to a greener grid and net zero, and finds it especially rewarding to see the positive impact renewable energy can have on both customers and the wider energy system.
Is adding a battery to a FIT solar system worth it?
For most households, yes. A battery stores any surplus electricity your solar panels generate during the day, allowing you to use it later instead of exporting it straight to the grid.
By making more use of your own renewable electricity, you can buy less energy from your supplier, reduce your reliance on the grid, and get even more value from your existing FIT solar system.
Battery storage is a great option for any FIT customers who:
- Are often out during the day while your solar panels are generating electricity.
- Use more electricity in the evenings.
- Regularly export unused solar power.
- Have, or are considering, a time-of-use electricity tariff.
Will a battery affect my FIT payments?
In many cases, no – but it depends on how your existing solar system is configured and how the battery is installed.
Your FIT generation payments are based on the electricity your solar panels generate, so adding battery storage doesn’t automatically affect them. However, the way your battery connects to your existing system, where it’s positioned in relation to your generation meter, whether it can charge from the grid and how your system is metered can all affect what changes, if any, are needed to help your system continue to meet FIT requirements.
- If you’re on deemed export, your export payments may remain unchanged, depending on how your battery is installed and how your existing FIT system is set up. In some cases, changes to your metering or export arrangements may be needed, and your installer will advise on the best approach.
- If you’re on metered export, adding a battery may reduce the amount of electricity you export, as more of the energy your panels generate is stored for use at home. Although this could reduce your export payments, many homeowners offset this by buying less electricity from their supplier.
Depending on your existing setup, changes to your metering arrangement or additional paperwork may be needed before installation. A qualified installer will assess your system, recommend the appropriate configuration and make sure your installation continues to meet FIT requirements wherever possible. In some circumstances, certain battery configurations may not be compatible with FIT requirements, which is why it’s important to assess each system individually before any work begins.
Most installers will need to know your current FIT and export arrangements before any work goes ahead. Not sure what type of export you’re on? As an energy supplier and installer, our team can help you find out.
What to expect when adding a battery to a FIT solar system
Adding a battery to a FIT solar system is straightforward with Good Energy.
Our expert team will:
- Check your existing solar system.
- Recommend a battery that’s suitable for your home.
- Confirm whether you’re on deemed or metered export.
- Support you through the paperwork needed for your FIT provider.
- Install and commission your battery.
- Make sure you continue to receive FIT payments.
If Good Energy is both your FIT provider and battery installer, we can coordinate lots of this process internally, meaning you can enjoy a smoother experience with less hassle.
Do I need to tell my FIT provider if I’m adding battery storage?
Yes – we always recommend that, before undergoing any work to your FIT solar system, you notify your FIT provider first.
This is a standard part of the process, and your installer can help make sure everything is completed correctly. This usually involves:
- A completed battery storage declaration form.
- Details of your battery, including its make, model and capacity.
- A clearly labelled Single Line Diagram showing how the battery connects to your existing solar equipment, including the site address.
We’ll review these documents to make sure your updated system continues to meet FIT requirements and that electricity generated, stored and exported can be measured correctly before confirming the appropriate payment arrangements.
If Good Energy is both your FIT provider and battery installer, we can coordinate more of the process internally. This can make updating your system and providing the necessary paperwork more straightforward than coordinating between separate companies.
How does a battery connect to FIT solar panels?
There are two main ways a battery can be added to an existing solar system.
Your installer will recommend the option that’s right for your home, so you can feel confident everything is set up correctly. And, whatever option you choose, the aim is the same: making sure the electricity your panels generate, the energy your battery stores and the electricity you export are all measured accurately so your FIT payments continue.
Option 1: AC-coupled batteries
This is the most common option for existing FIT systems.
The battery is added alongside your existing solar equipment, which often makes installation simpler and means fewer changes to your current setup.
If you also want to charge your battery from the grid using a cheaper overnight tariff, your installer may recommend additional metering to make sure imported electricity isn’t confused with solar generation.
Option 2: DC-coupled batteries
A DC-coupled battery connects before the inverter, which usually means replacing your existing inverter with a hybrid model.
This can be a good option if your inverter is already nearing the end of its life, but it’s generally a larger upgrade than an AC-coupled system. If you replace your inverter, you’ll also need to notify your FIT provider.
What’s the best battery to add to a FIT solar system?
The best battery for FIT solar systems is one that matches how much electricity your home generates and uses. Most UK homes see good value from batteries in the 5–15kWh range, but the right size depends on your home and energy use.
The best battery installer for FIT solar systems will recommend a battery that’s right for your property rather than simply the biggest one available.
Thinking about adding a battery to your FIT solar system?
As one of the UK’s largest and most experienced voluntary Feed-In Tariff administrators, our experts have years of experience helping homeowners upgrade their existing systems. We’ll make sure everything is installed correctly and all the necessary paperwork is taken care of – ensuring your payments aren’t put at risk.
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Battery storage for FIT solar systems FAQs
Yes. In most cases, battery storage can be added to an existing solar PV system without replacing your solar panels. Your installer will assess your current setup and recommend the most suitable battery and connection method for your home.
There are several ways a battery can be added to an existing solar system.
Your installer will recommend the option that’s right for your home, so you can feel confident everything is set up correctly.
Some batteries are installed alongside your existing solar equipment, while others may require additional components or upgrades. In certain cases, additional metering may also be recommended to ensure imported electricity isn’t confused with solar generation.
Whatever option you choose, the aim is the same: making sure the electricity your panels generate, the energy your battery stores and the electricity you export are all measured accurately so your FIT payments continue as expected.
Exactly how much you’ll save depends on:
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- Your solar system size.
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- How much electricity your household uses.
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- Whether you’re on deemed or metered export.
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- Whether you’re on a time-of-use tariff.
If you get in touch with our team, we’ll review your existing solar system, your energy usage and your FIT setup to understand how a battery could work for your home. We’ll then put together a personalised proposal, including our recommended battery, estimated installation costs and savings potential.
Not always. Many existing solar systems can have an AC-coupled battery added without replacing the inverter. However, some battery systems require a hybrid inverter, particularly if you’re choosing a DC-coupled setup. Your installer will explain which option is right for your system.
Most battery installations are completed within a day, although this depends on your existing solar system and whether any additional electrical work or metering is required. Before installation, your installer will confirm what’s involved and provide a clear timeline.
Most home battery systems automatically switch off during a power cut for safety reasons. If having backup power is important to you, speak to your installer about batteries that offer backup functionality, such as the Tesla Powerwall 3.
In most cases, no. Battery storage is usually covered by permitted development rights, meaning planning permission isn’t required. Your installer will let you know if there are any exceptions for your property.
Yes. We can assess many existing solar PV systems, even if they were installed by another company. Our team will review your current setup and advise whether battery storage is suitable for your home.
The easiest way to find out is to have your existing solar system assessed by an experienced installer. We’ll check your current equipment, understand how you use electricity at home and recommend whether battery storage is likely to be worthwhile for you.
Not usually. If set up by a good installer, adding a battery to a FIT solar system shouldn’t affect your FIT generation payments. However, there are additional steps that need to be taken in order to protect your payments. Your installer and FIT provider will need to review your metering arrangements and complete some additional paperwork.
In some cases, certain meter configurations (particularly, bi-directional) can result in negative readings, which aren’t eligible for FIT payments. Your installer and FIT provider will check your system to help avoid this.
While some system set ups may reduce your payments marginally, this is usually outweighed by the savings a battery can provide. By using more of the renewable electricity you generate yourself, most homeowners reduce the amount of electricity they need to buy from the grid, making battery storage very financially beneficial overall.
Choosing an experienced installer helps protect your ongoing FIT payments. When adding a battery to a FIT solar system, a professional installer will make sure:
- Your FIT provider is notified about the battery installation.
- Your battery is compatible with your existing solar system.
- Any additional metering that’s needed is installed correctly.
- All MCS certification and commissioning paperwork is completed.
