If you are shortlisting home batteries, Sigenergy, GivEnergy, Fox ESS and Sunsynk tend to come up together. They are all serious brands, they all use lithium iron phosphate batteries, and they can all store your solar for the evening. They are built in quite different ways, though, and that difference matters more than any single spec. We have installed all four for customers across Dorset, Hampshire and Wiltshire, so here is an honest installer’s comparison.
The short answer
- Sigenergy suits homes that want one tidy, modular system covering solar, battery, backup and EV charging, with room to grow.
- GivEnergy suits homes that want a large, simple battery with strong UK support, especially when adding a battery to existing solar.
- Fox ESS suits homes that want a flexible, high-voltage modular battery with lots of capacity options.
- Sunsynk suits more technical setups: larger single phase systems, off-grid style designs and owners who like to tinker.
None of them is the best for everyone. The right one depends on your roof, your existing kit, your tariff and whether you want backup or EV charging.
How each system is built
Sigenergy SigenStor
SigenStor stacks a hybrid inverter, called the Energy Controller, on top of battery modules to make one tower. Sigenergy’s datasheet gives two module sizes, 5.2 kWh and 7.8 kWh usable, with one to six modules per controller. Each module has its own DC optimiser, which is why newer modules can be added to an older stack. It comes in single phase and three phase versions, adds backup through the Sigen Gateway, and can include a DC EV charging module in the same stack. Our SigenStor guide goes into the detail.
GivEnergy All in One
GivEnergy’s All in One is a single large AC-coupled unit with the battery and inverter in one box. GivEnergy’s UK datasheet lists 13.5 kWh capacity, 6 kW continuous power and a 12 year warranty. Because it is AC-coupled, it sits alongside your existing solar inverter rather than replacing it, which makes it a natural fit for retrofits. GivEnergy also makes hybrid inverters with separate batteries for new solar installs.
Fox ESS
Fox ESS pairs its hybrid inverters with stackable high-voltage battery modules. Fox’s EQ4800 datasheet lists 4.66 kWh modules, with up to nine in one stack for a little under 42 kWh. That fine-grained sizing is useful when you want to match capacity closely to your usage. Inverters come in single and three phase.
Sunsynk
Sunsynk is best known for its hybrid inverters, which pair with Sunsynk batteries and a published list of compatible batteries from other makers. The inverters cover a wide range of power ratings, including large single phase models, and offer a lot of configuration. That flexibility is why installers use them for off-grid style setups and unusual sites, but it also means setup and settings are more technical than the others here.
Side by side
| Sigenergy | GivEnergy | Fox ESS | Sunsynk | |
|---|---|---|---|---|
| Design | Modular all-in-one stack | Single all-in-one unit (AIO), or inverter plus batteries | Hybrid inverter plus stackable HV modules | Hybrid inverter plus batteries |
| Battery sizing | 5.2 or 7.8 kWh modules, 1 to 6 per controller | 13.5 kWh (All in One) | 4.66 kWh modules, up to 9 per stack | Depends on battery chosen |
| Adds to existing solar | Usually by replacing the old inverter | Yes, the AIO is AC-coupled | Yes, with an AC-coupled setup | Yes, depending on design |
| Three phase | Yes | Yes, selected models | Yes | Yes |
| Backup | With Sigen Gateway | With GivEnergy Gateway | Yes, with backup wiring | Yes, a core strength |
| Integrated EV charging | Optional DC module in the stack, plus AC charger | Separate charger | Separate charger | Separate charger |
| Best for | Growing households, EV owners, three phase homes | Simple large battery, retrofits | Flexible sizing | Technical and off-grid style systems |
Specs change as manufacturers update their ranges, so we confirm the current model and datasheet at survey for whatever we recommend.
Where Sigenergy wins
- Everything in one place. Solar, battery, backup and EV charging in one system and one app.
- Growing later. Adding modules to an older stack is designed in from the start.
- Complicated roofs. Multiple solar inputs on the Energy Controller handle panels on two or three roof faces well.
- Smart tariffs. Sigen AI Mode can plan around dynamic prices. See our mySigen app guide.
Where the others win
- GivEnergy is a UK company with a long UK track record and a large installed base, and the All in One is about as simple as a big battery gets. For adding storage to a solar system that is already working, it is often the most straightforward route.
- Fox ESS gives very flexible sizing in smaller steps, which can be handy when you want to match the battery closely to your usage.
- Sunsynk is hard to beat for configurability, larger single phase systems and setups designed around backup.
- Track record. Sigenergy was founded in 2022, so it has the shortest history of the four in UK homes. The hardware is well regarded, but there is less long-term field data.
How we decide what to recommend
We do not start with a brand. We start with your home: your current solar (if any), your roof, single or three phase supply, how much you use and when, your tariff, and whether you want backup or EV charging now or later. Then we recommend the system that fits, and we explain why. Sometimes that is Sigenergy. Often it is GoodWe, our most-installed brand, which we compare in Sigenergy vs GoodWe. Our battery storage page covers the full range we install.
FAQs
Is Sigenergy better than GivEnergy?
Not across the board. Sigenergy is stronger for an all-in-one system with EV charging and room to expand. GivEnergy is often simpler for adding a large battery to existing solar, and it has a longer UK track record.
Is Sigenergy better than Fox ESS?
They are closer than most comparisons. Both are modular. Sigenergy integrates more into one stack and one app, while Fox ESS offers finer battery sizing steps. Your home decides it.
Which is best for a power cut?
All four can provide backup when designed and wired for it. How much of the house stays on depends on the inverter power, the battery size and the backup wiring, not just the brand.
Can I mix brands?
Generally no. Batteries need to be matched to a compatible inverter, so we design the system as a whole.
Talk to a local Sigenergy installer
Not sure which of these suits your home? We install all four, so you will get a straight answer rather than a sales pitch. See our Sigenergy installer page or request a free, no-obligation quote for Dorset, Hampshire and Wiltshire. You can also call us on 01202 985 888.