The idea behind solar battery storage is simple. You store the solar energy your panels produce during the day so you can use it later, once the sun’s gone down and your panels have stopped generating.
Without a battery, that surplus energy just goes back to the grid, and you get paid whatever your export tariff happens to offer that day, which is often a fraction of what you’d pay to buy the same electricity back. It’s a bit backwards when you think about it. You install solar panels to cut your energy costs, then send a big chunk of what you generate straight back out for pennies, only to buy electricity in the evening at full price. A battery is what closes that gap.
If your solar was installed years ago under the old Feed-in Tariff, that scheme closed to new applicants back in 2019, so if you’re still on it, none of this affects your existing FiT payments. Adding a battery today doesn’t change how your generation is measured for FiT purposes. Anyone installing solar now is on the Smart Export Guarantee (SEG) instead, which pays for what you actually export, measured properly through a smart meter rather than assumed. That difference matters, because it means every kWh you store and use yourself instead of exporting is now a direct, measurable saving rather than a rough estimate.
What batteries actually cost you in savings
The math hasn’t really changed, it’s just got more favourable as electricity prices have crept up. If your import rate is around 30 to 35 pence per kWh and you use 6kWh a day from stored battery power instead of buying it from the grid, that’s roughly £2 a day. Over a year, that’s not far off £700 to £750 in savings, and that’s before you factor in charging your battery cheaply overnight on a smart tariff and using it during the expensive evening peak.
Speaking of which, that’s the other big advantage. Suppliers like Octopus offer overnight import rates that can sit well under 10p per kWh, and export tariffs like Intelligent Octopus Flux can pay considerably more than a basic SEG rate during the late afternoon peak, when demand is highest. A battery lets you take advantage of both ends of that, charging cheap and either using or exporting at the point where it’s worth the most.
Which battery should you actually get?
This is where it gets more interesting than it used to be. A few years ago the market was mostly small, fairly basic lithium units. Now there’s a genuine range of well engineered systems, and which one makes sense for you depends on your budget, your roof, whether you drive an EV, and how much you want the system to do beyond just storing energy. Here’s what we install most, and why.
Hanchu ESS is our go-to for straightforward, cost effective retrofits. It’s a modular AC coupled system, which means it sits alongside your existing inverter rather than replacing it, so it’s a genuinely simple add-on if you’ve already got solar panels installed and just want to stop wasting your export. Hanchu batteries run LFP cells with a 95% depth of discharge, meaning you get to use almost all of the capacity you’re paying for, and the warranty on the battery modules runs to 12 years, longer than most of the market. If your priority is a clean, no-fuss retrofit at a sensible price, this is usually where we start the conversation.
Fox ESS has become one of the most installed battery brands in the UK, and for good reason. It’s a modular stackable system, so you can size it to your household rather than being locked into one fixed capacity, running from a single 5kWh-ish module right up to around 46kWh stacked. It pairs with a Fox ESS hybrid inverter and sits on the Intelligent Octopus Flux approved list, so if you’re on that tariff the whole thing can be automated to charge and export at the most profitable times without you having to think about it. Ten year warranty, strong round trip efficiency, and a solid balance of price and performance.
Sigenergy SigenStor is the one to look at if you drive an electric vehicle or think you might. It’s built as an all in one system, combining the inverter, the battery and EV charging into a single unit, including bidirectional charging so your car’s battery can effectively become part of your home storage too. It’s modular from around 6kWh up to over 50kWh, has a genuinely fast, near instant switchover during a power cut, and a ten year warranty. It’s a newer brand than some of the others on this list, but the technology and the backing behind it are solid, and we’ve had good results fitting it.
Tesla Powerwall 3 sits at the premium end, and it earns that position. It’s a single fixed size unit at 13.5kWh usable, with the inverter built in, which simplifies installation if you’re doing solar and battery together. The output rating is high enough to comfortably run demanding appliances like an electric shower or a heat pump without the system struggling, and the Tesla app is about as polished as monitoring software gets in this space. It costs more than the alternatives above, but if you want the most capable single unit on the market with the strongest brand backing, it’s the one most people ask for by name.
All four run LFP (lithium iron phosphate) chemistry, which is the safest lithium battery type currently available for home use, and all come with strong manufacturer warranties as standard.
Can I add a battery if I already have solar panels?
Yes, and this is one of the most common jobs we do. There are two ways to retrofit a battery onto an existing solar system.
The first is an AC coupled setup, which is what Hanchu typically uses. It sits completely separately from your existing inverter, with a current clamp on your incoming supply that tells the battery when to start charging from surplus solar. It’s a straightforward add-on that doesn’t touch your existing kit.
The second is replacing your current inverter with a hybrid inverter, which handles both the solar and the battery charging in one unit. This is generally the neater long term option and how Fox ESS, Sigenergy and Tesla systems typically work, but it does mean swapping out your existing inverter rather than just adding to it.
Which route makes sense depends on your existing setup, and it’s exactly the kind of thing we’ll walk through on a survey.
A word of caution
You’ll still come across companies offering a “free system health check” that somehow always ends with a recommendation to buy a battery, often at an inflated price, sometimes from someone on commission with very little actual solar knowledge. If your generation figures haven’t visibly dropped, be sceptical of anyone telling you your system is “only working at 35% efficiency” off the back of a five minute look at your inverter. That’s still a live tactic in 2026, so it’s worth knowing what to watch for.
What kind of savings can I realistically expect?
Without a battery, most households only self consume around 25 to 30% of what their solar panels actually generate, because so much of it is produced in the middle of the day when nobody’s home to use it. Add a properly sized battery and that self consumption rate can climb to 80% or higher, meaning far more of the electricity you generate for free is actually used by your household rather than sold back to the grid for a fraction of its value.
Getting it done properly
Spectra Solar is fully qualified to design, install and commission battery storage systems, and we handle the G98 or G99 grid notification on your behalf as part of the job, so there’s no separate admin for you to sort out with your network operator.
If you’re weighing up whether a battery makes sense for your home, or you want to know which of Hanchu, Fox ESS, Sigenergy or Tesla actually suits your setup, get in touch and we’ll talk it through properly. You can also head straight to our quote page for a free, no obligation survey.