Can You Add More Batteries to Your Solar System? (2026 Guide)
Yes — but whether it's straightforward depends on your existing inverter. If you have a hybrid inverter, adding a compatible battery is usually a half-day job. If you have a standard string inverter, you'll need to replace it first, which adds cost and complexity.
The inverter question
Your inverter determines what's possible.
Hybrid inverter — handles both solar input and battery charging in one unit. Adding a compatible battery is plug-and-play in most cases. Common hybrid inverters include GivEnergy, SunSynk, Solis, and SolarEdge. Each manufacturer maintains a compatibility list of approved batteries.
Standard string inverter — converts solar DC to AC only. It has no built-in battery management. To add storage, you either replace it with a hybrid inverter (£800–£1,500 for the inverter plus labour) or add an AC-coupled battery system alongside the existing inverter. AC-coupled systems like the Tesla Powerwall or GivEnergy AC battery work without touching your existing inverter.
Microinverters — similar to AC-coupled. You'd add an AC battery alongside the existing system rather than replacing anything.
If you're not sure which inverter you have, check the label on the unit in your loft or consumer unit room. Your original installer should also have the details on record.
Can you have more than one battery?
Yes. Most residential hybrid inverters support multiple batteries in a stacked configuration, up to the inverter's maximum battery input rating. Common setups:
| Configuration | Total storage | Typical use case |
| 1 × 5kWh | 5kWh | Small household, limited budget |
| 1 × 10kWh | 10kWh | Average 3-bed home |
| 2 × 10kWh | 20kWh | Larger home or EV charging |
| 3+ batteries | 25–30kWh+ | High usage, off-grid backup aspiration |
Batteries should be the same brand and ideally the same model when stacking. Mixing brands is possible in some configurations but can cause BMS (battery management system) conflicts and may void warranties.
What does it cost to add a battery in 2026?
Approximate installed costs in the UK:
| Battery | Capacity | Approximate installed cost |
| GivEnergy 9.5kWh | 9.5kWh | £2,800–£3,500 |
| Pylontech US5000 | 4.8kWh | £1,800–£2,400 |
| SunSynk 5.32kWh | 5.32kWh | £2,200–£2,900 |
| Tesla Powerwall 3 | 13.5kWh | £7,000–£9,000 inc. inverter |
Solar batteries are VAT-exempt (0%) when installed alongside or as part of a solar system, which previously added 20% to the cost.
Which batteries are recommended in 2026?
The most widely installed residential batteries in the UK:
GivEnergy — strong software platform, wide inverter compatibility, good UK support. Their AIO (all-in-one) units combine inverter and battery.
Pylontech — reliable, widely supported, one of the most tested batteries in the market. Modular design makes expansion simple.
SunSynk — popular with installers for their hybrid inverters and matching batteries. Good monitoring app.
Tesla Powerwall 3 — premium option with integrated inverter, excellent software, high upfront cost. Works best as a complete system rather than a retrofit.
Lithium iron phosphate (LFP) chemistry is now standard across most residential batteries. LFP is safer than older lithium-cobalt chemistry, handles more charge cycles (typically 4,000–6,000 at 80% depth of discharge), and degrades more slowly over its lifespan.
Will adding a battery void your solar warranty?
It can, if the battery installation isn't done correctly or if an incompatible component is used. To protect your existing warranty:
- Use an MCS-accredited installer for the battery work
- Confirm compatibility with your inverter manufacturer before ordering
- Keep documentation of the installation for your records
Most reputable installers will check this before quoting. If you're getting a quote and nobody mentions warranty implications, that's a flag.
Is it worth adding a battery if you don't have solar?
Yes, in some circumstances. AC-coupled batteries can charge from the grid overnight on cheap-rate tariffs (such as Octopus Go or Economy 7) and discharge during peak hours, reducing your bills without solar panels. The economics are tighter than pairing with solar, but it's a genuine option for households that can't install panels (flat dwellers, renters with landlord permission, north-facing roofs).
Getting a quote
The fastest route is a free survey, which lets an installer confirm your inverter compatibility, assess your cable routes and consumer unit, and size the battery to your actual usage data. CRG Direct carries out battery retrofit surveys across Hampshire and the surrounding area.