Rated 4.8 on Trustpilot
Read Reviews
Battery storage · London
Solar Battery Storage in London
Fitted with new solar, or added to the panels you already have. MCS-certified, family-run, based in London.
Solar Panels London designs and installs home battery storage across every London borough and the surrounding counties. We fit batteries as part of a new solar system and we retrofit them to existing solar — including systems installed by other companies and older Feed-in Tariff systems.
We install Hanchu, FoxESS and Sigenergy storage, so the system is matched to the house rather than to whatever we happen to stock. Every installation is MCS-certified, we handle the DNO paperwork, and you get a written workmanship guarantee alongside the manufacturer warranties.
Already have solar panels? You can almost certainly add a battery
Yes — in the majority of cases an existing solar PV system can have a battery added. There are two ways to do it, and which is right depends on your current inverter, its age, and whether you want backup power.
Option 1
AC-coupled battery — keep your existing inverter
The battery comes with its own inverter and connects to your home’s electrics alongside your existing solar system. Your solar inverter is left alone. This is usually the simplest retrofit, it keeps any manufacturer warranty on your existing inverter intact, and it is generally the route we prefer where the existing system is working well.
Option 2
Replace your inverter with a hybrid
A hybrid inverter handles both the panels and the battery. This makes sense when your existing inverter is near the end of its life — many string inverters last 10 to 15 years — when it has already failed, or when you want the tidiest system with one monitoring app. It means replacing a working inverter, so we only recommend it where it earns its keep.
What about my Feed-in Tariff?
Adding a battery does not normally end your FIT payments, but the connection method matters. An AC-coupled battery sits on the house side of your generation meter, so the meter carries on recording exactly what your panels produce. If we replace your inverter with a hybrid, we fit a bidirectional meter so that electricity used to charge the battery from the grid is never counted as generation. Either way your FIT payments continue, and we will tell you if your FIT licensee needs to be notified.
Buying solar and battery together
If you are installing solar for the first time, a hybrid inverter with a battery is the cleanest design: one inverter, one app, and the option of backup power built in from day one. Our Better, Best and Elite packages are all built this way — FoxESS hybrid inverters with FoxESS batteries, and a Sigenergy SigenStor system for the Elite package.
Our surveyor sizes the solar and the battery together, so the battery is matched to what the roof can actually generate and to how your household uses electricity, rather than sold as a fixed bundle.
See our solar and battery packages · Solar panel installation in London
How a home battery works
During the day your panels generate more than the house is using. Without a battery, the surplus is exported to the grid for a few pence per unit. With a battery, that surplus is stored and used in the evening and overnight when the panels are off — so you buy less electricity at the full import price.
Most modern batteries can also be charged from the grid on a time-of-use tariff, so on dull winter days the battery fills up with cheap overnight electricity and discharges during the expensive peak. That is why a battery can make sense even for homes with a modest solar array.
Daytime
The house takes what it needs, the surplus fills the battery, and only what is left over is exported.
Evening and overnight
The panels have stopped, so the battery runs the house. On a time-of-use tariff it can also refill from the grid at the cheap rate.
The batteries we install
Three ranges, chosen because we install and monitor them ourselves and are happy standing behind all of them. All three use lithium iron phosphate cells, all three can go in a garage or on an outside wall, and all three carry a 10-year manufacturer warranty as standard. Each is strongest at something slightly different, and the survey is what decides which one suits your house.
Safety and cold-weather performance
Hanchu ESS
A safety-led design, and the one we reach for when a battery has to cope with a cold, exposed location. It uses blade-format cells built to automotive standards, integrated heating keeps it charging and discharging properly through a British winter, and it carries the longest warranty of the three.
- Home-ESS-HV — 2.7 kWh and 5.12 kWh modules, stacked to the capacity you need.
- CESS-HV — 9.4 kWh, for larger homes or where you want fewer units on the wall.
- IP65 rated, so it can go outside as well as in a garage or utility room.
Warranty is 10 years, extending to 12 when the system is registered and kept online, with a performance warranty covering 60% of usable capacity to 12 years or 6,000 cycles.
Our most-installed system
FoxESS
The system we install most, because it fits the widest range of houses. Well proven in UK homes, with a built-in heating element and built-in fire suppression on the EP batteries, three module sizes to size a system precisely, and a monitoring app that is genuinely usable.
- EP6 — 5.76 kWh per unit, up to four units. A good fit for smaller homes, or for starting modestly and adding a second unit later.
- EP12 — 11.52 kWh per unit, up to four units. Suited to a typical three- to four-bedroom home with a 4–6 kW array, or anyone with an EV.
- CQ7 — Fox’s newest plug-and-play modular battery, 7 kWh per module, stacking from two modules upwards.
All are IP65 rated for indoor or outdoor installation. They pair with FoxESS hybrid inverters on new systems and FoxESS AC-coupled units on retrofits, and are monitored through the FoxESS Cloud app. Warranty is 10 years once registered.
Backup and EV charging in one unit
Sigenergy SigenStor
The system in our Elite package, and the most integrated of the three. The hybrid inverter, the battery modules and, if you want it, a DC EV charger all stack together as a single unit, which keeps a large system looking like one tidy tower rather than a wall of boxes.
- Battery modules of 6 kWh and 10 kWh, which we stock, stacking to build the capacity you need in one tower.
- Single-phase hybrid inverters from 3.6 kW upwards, with three-phase options.
- Optional Sigen Gateway for whole-home backup with no noticeable interruption when the grid fails.
- Monitored and controlled through the mySigen app, including automated tariff-based charging.
Our recommendation where you want backup for the whole house, integrated EV charging, or a system you can keep growing.
Which one we put in front of you depends on the survey — the roof, how much you use in the evening, whether you want backup, and how much room the location gives us. We will tell you why we have recommended one over another rather than leaving you to guess.
What size battery do I need?
There is no single right answer, which is why we survey rather than quote from a form. The size that suits you depends on:
- how much electricity you use, and when — evenings and overnight matter most
- the size of your solar array, existing or planned
- whether you have, or plan, an EV charger or a heat pump
- whether you are on, or could move to, a time-of-use tariff
- whether you want backup power, and for which circuits
As a rule of thumb, a smaller household with a modest array is usually well served by a single-digit kWh battery, while larger homes, EV owners and heat pump users often justify 10 kWh or more. Oversizing a battery you can never fill is money wasted; undersizing means still importing at peak. Our survey report shows you the reasoning behind the size we recommend.
Will a battery keep the lights on in a power cut?
Only if it is designed to. This is the question we are asked most, and the honest answer is that a standard battery installation switches off in a power cut, exactly like a standard solar system, because it is not allowed to feed electricity into a dead grid.
There are two levels of backup:
EPS — emergency power supply
Many hybrid inverters, FoxESS included, have an EPS output that can keep selected essential circuits running — typically lighting, the fridge-freezer, broadband and a few sockets. There is a brief switchover, and the output is limited by the inverter’s EPS rating.
Whole-home backup
A gateway, for example the Sigen Gateway, sits between the grid and your consumer unit and can back up the whole house with no noticeable interruption, subject to the battery’s power and capacity.
Both need extra electrical work at installation and must be planned in from the start, so if backup matters to you, say so at the survey.
Where the battery goes
Batteries in homes are installed to the fire-safety specification PAS 63100:2024, which our designs follow. In practice this means a battery is not installed in a loft or roof void, on an escape route such as a hallway, stairs or landing, or in a bedroom. Good locations are usually a garage, a utility room, a plant cupboard with the right access, or an outside wall with a weatherproof unit.
For London terraces and flats where space is tight, this is often the deciding factor in the design, and our surveyor will confirm a compliant location before we quote.
DNO approval, MCS and paperwork
A battery inverter is treated as a generator by your electricity network operator — in London, mostly UK Power Networks — so every battery installation needs a DNO notification or application:
- G98 — a notification after installation for smaller systems, up to 3.68 kW of inverter output per phase in total, solar and battery combined.
- G99 — an application before installation for anything larger, or where export limiting is used. Approval typically takes a few weeks, so we build it into the programme.
We handle the application, the MCS certificate and the handover pack. We also register the battery warranty with the manufacturer for you.
0% VAT on home batteries until 31 March 2027
The installation of battery storage in a home is zero-rated for VAT in Great Britain — including a battery added to an existing solar system — until 31 March 2027. From 1 April 2027 the rate is due to return to 5%. It applies to the installed system, so the saving is on labour as well as equipment.
Fact-checked 2 September 2026. We will update this section if the Autumn Budget changes the date.
What’s included in your battery quote
How long does it take?
Most single-battery retrofits are completed in a day. New solar and battery installations usually take one to two days depending on the roof, and where scaffolding is required it goes up a few days beforehand. If your system needs G99 approval, the DNO’s response time is the longest part of the process, and we tell you the expected timeline at quote stage.
Covering London and the surrounding counties
We install batteries in every London borough and up to roughly 40 miles beyond the M25. Our engineers are London-based, which matters for aftercare: if you need us, we come out.
Frequently asked questions
Can I add a battery to solar panels installed by another company?
Yes. We quote for systems we did not install. We check the existing inverter and panels at survey, and in most cases an AC-coupled battery can be added without touching them.
Can I charge the battery from the grid overnight?
Yes, with a time-of-use tariff. All three of the ranges we fit — Hanchu, FoxESS and Sigenergy — can be scheduled to charge during the cheap window and discharge at peak. We set this up at handover.
Will a battery power my whole house in a power cut?
Not by default. A standard installation shuts down in a power cut. Backup has to be designed in — either an EPS output for essential circuits, or a gateway for whole-home backup.
Can I add more battery capacity later?
Usually yes. Hanchu, FoxESS and SigenStor batteries are all modular, so extra modules can be added within the limits of the inverter and the location. Tell us if you expect to add an EV or a heat pump and we will design in the headroom.
Do I need planning permission for a battery?
Domestic battery storage does not normally need planning permission, though listed buildings and some external locations can be exceptions. We flag anything that needs checking at survey.
Where can the battery be installed?
Garages, utility rooms and suitable external walls are typical. Lofts, escape routes and bedrooms are ruled out by the PAS 63100 fire-safety specification. Our surveyor confirms a compliant location before quoting.
How long do solar batteries last?
The lithium iron phosphate batteries we install carry 10-year manufacturer warranties, and the chemistry is designed for several thousand charge cycles — one cycle a day for well over a decade in normal use. Capacity reduces gradually rather than failing suddenly.
Is a battery worth it if I do not have a big solar array?
It can be, because of time-of-use charging: the battery fills with cheap overnight electricity and covers the expensive evening peak whether or not the sun shone. Whether it pays back for you depends on your usage and tariff, which is what the survey works out.
Request your free battery survey
Tell us whether you already have solar, roughly what you spend on electricity, and your postcode. We respond within 24 hours, and you will have an honest written quote within 48 hours of the survey — no pressure, no inflated savings.
Written by Marcus, Director, Solar Panels London. Last reviewed 2 September 2026. Product specifications are manufacturer figures and battery sizing, backup and installation location are always subject to a site survey.
Rated 4.8/5 on Trustpilot from 41 reviews
Quick Links
Services
Contact
© 2026 Solar Panels London. All rights reserved.