The short answer
There is no single 'best' solar battery — the right one depends on your usage, budget and inverter setup. Most home batteries now use lithium iron phosphate (LFP) chemistry, which is safe and long-lived. The well-known UK options include the Tesla Powerwall (large all-in-one unit with its own inverter), GivEnergy (modular British-supported systems), and Pylontech (widely used modular battery modules), among others such as SolarEdge, Sonnen, Fox ESS, Puredrive and Duracell. When comparing, look at usable capacity (kWh) rather than nominal, the depth of discharge, the warranty (often ~10 years or a stated number of cycles/throughput), whether it is AC- or DC-coupled, and the round-trip efficiency. Size the battery to your evening and overnight use, not the biggest number.
A battery stores your surplus solar electricity for use after dark, cutting how much you import from the grid. Brand searches are popular, but the sensible approach is to compare the specs that affect day-to-day value and size the battery to your home. Here is how.
Comparing batteries
- Common chemistryLithium iron phosphate (LFP)
- Key figureUsable kWh, not nominal
- Typical warranty~10 years or cycle/throughput
- Depth of dischargeOften ~90–100% on LFP
- Right sizeMatched to evening use
What to compare on a battery
Capacity is quoted in kilowatt-hours (kWh), but the figure that matters is usable capacity — the energy you can actually draw, after the depth-of-discharge limit. A battery's nominal capacity may be higher than what you can use, so compare usable kWh. Depth of discharge (DoD) is the share you can safely use; modern LFP batteries allow a high DoD, often around 90 to 100%.
Warranty is the other big factor. Batteries are usually warranted for around ten years, or for a stated number of cycles or a total energy throughput (the lifetime kWh it will deliver), whichever comes first. Round-trip efficiency — how much energy you get out versus put in — is typically in the high 80s to mid 90s percent for good lithium batteries. Together these tell you how much usable storage you are really buying and for how long.
| Spec | What to look for | Why it matters |
|---|---|---|
| Usable capacity | Stated usable kWh | What you can actually store and use |
| Depth of discharge | High (often ~90–100%) | More of the battery is usable |
| Chemistry | LFP common today | Safe, long cycle life |
| Warranty | ~10 yrs or cycles/throughput | How long it is warranted |
| Round-trip efficiency | High 80s–mid 90s % | Less energy lost in storage |
| Coupling | AC or DC | Affects install and retrofit |
What to weigh when comparing batteries. Sources: Energy Saving Trust.
The main UK options
The Tesla Powerwall is a large all-in-one unit with its own inverter built in, popular for its capacity and app, and suited to homes wanting a single sizeable battery. GivEnergy is a British-supported brand offering modular batteries and hybrid inverters, often chosen for local support and flexible sizing. Pylontech supplies widely used modular battery modules that many installers pair with a compatible hybrid inverter, letting you stack capacity to suit.
Other names you will see include SolarEdge (which pairs with its optimiser ecosystem), Sonnen, Fox ESS, Puredrive and Duracell Energy, among others. As with panels, this is not a ranking — several are sound, and availability and models change. The right pick depends on the capacity you need, whether you want a modular or all-in-one unit, your inverter, and the support and warranty on offer.
Sizing, tariffs and how to choose
Sizing well is more important than chasing a brand. The goal is to store enough daytime surplus to cover your evening and overnight use, so look at how much electricity you use after the sun stops generating. A battery much larger than that will sit part-empty and pay back slowly; one too small will fill and export the rest. Your installer can model this from your usage.
Batteries also enable smart, time-of-use tariffs: with the right tariff you can charge the battery from the grid during cheap overnight periods and use it during expensive peak hours, on top of storing your own solar. This can improve the economics noticeably, so consider the battery and tariff together rather than in isolation. Some batteries and hybrid inverters handle this scheduling better than others.
To choose, decide the usable capacity you need from your evening and overnight consumption, then compare batteries on usable kWh, warranty terms (years and cycles/throughput), efficiency, and whether AC- or DC-coupling suits your situation — DC-coupling is common for new installs, AC-coupling for adding a battery to existing panels. Use an MCS-certified installer and get more than one quote, comparing the whole system. As with panels, several reputable batteries will serve you well; the win is in correct sizing and a competent install.
Frequently asked questions
What size solar battery do I need?
Size it to your evening and overnight electricity use, when solar is not generating. The aim is to store enough daytime surplus to cover that demand. A battery much larger than your typical after-dark use will sit part-empty and pay back slowly. Your installer can model the right size from your usage figures.
What is the difference between AC and DC coupled batteries?
DC-coupled batteries connect on the panel side through a hybrid inverter and are common for new installs, often slightly more efficient. AC-coupled batteries have their own inverter and connect on the household AC side, which makes them convenient for adding storage to an existing solar system. Both work well; the choice depends on your setup.
How long do solar batteries last?
Most home lithium batteries are warranted for around ten years, or a set number of cycles or total energy throughput, whichever comes first. Modern lithium iron phosphate (LFP) batteries have long cycle lives and often retain a high share of capacity at end of warranty. Real lifespan depends on how heavily you cycle the battery.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific home. They are guidance, not a quotation or guaranteed saving.