These are the two home batteries people ask us about by name. They are both good products, and they are built around different ideas: Powerwall 3 is one large unit designed to be the only box on the wall, while SigenStor is a modular stack designed to be sized to the house and grown later. Here is how they compare on the things that decide a purchase, using only figures from the manufacturers’ and distributors’ published documents, which are linked at the end.
The short version
If you are having solar and a battery installed together and want the system to fit the house now and grow later, we recommend SigenStor for most homes. If you want a single large unit, have a roof big enough to fill 13.5 kWh regularly, and have confirmed the installer’s standing with Tesla in writing, a Powerwall 3 is a strong product. Both are available from Green Tech Hub: we supply, install and commission Sigenergy SigenStor systems, and we supply and install Tesla Powerwall 3.
| Sigenergy SigenStor | Tesla Powerwall 3 | |
|---|---|---|
| Capacity | 5 or 8 kWh modules, 1 to 6 per stack (up to 30 or 48 kWh), up to 10 stacks | 13.5 kWh per unit; up to 4 Powerwalls plus 3 Expansion units (7 units, 94.5 kWh) |
| Inverter | Hybrid, 3 to 12 kW single-phase, 5 to 30 kW three-phase | Integrated solar inverter |
| Backup | Built in, 0 ms switchover | With Backup Gateway 2; none with the Remote Meter configuration |
| EV charging | Optional DC EV charger module | Separate charger |
| Ingress rating | IP66 | IP55 enclosure, IP67 battery |
| Warranty | 10 years product warranty; retention terms on the datasheet | 10 years; 80% capacity at year ten; unlimited cycles for self-consumption, time-based control and backup, 37.8 MWh cap for other uses |
| Published UK price | None | £5,000 without Gateway, £5,975 with, excluding VAT, delivery and installation |
| Installer condition | MCS for your export tariff and insurer | Warranty applies only to units bought from Tesla or a Tesla certified installer |
Capacity, and how you grow it
This is the biggest practical difference. A Powerwall 3 is 13.5 kWh, full stop; if you need more you add a second Powerwall or an Expansion unit, and Tesla’s limit is four Powerwalls plus three Expansions, seven units and 94.5 kWh, far beyond a house. For a typical semi, 13.5 kWh is more than an evening’s use, which is fine if the roof can fill it and a waste if it cannot.
SigenStor is sized in 5 kWh or 8 kWh steps. Two 5 kWh modules suit an ordinary evening; three 8 kWh modules suit a home with an EV and a heat pump. A module can be added later without replacing anything. For a household whose electricity use is about to change, a car in two years, a heat pump in five, that granularity is worth a lot.
Inverter and grid connection
SigenStor’s hybrid inverter runs from 3 kW to 12 kW on single-phase and 5 kW to 30 kW on three-phase, and the size we fit most in homes is 5 or 6 kW. Powerwall 3 has its solar inverter built in. Either way, expect a G99 application: a generator above 16 A per phase, 3.68 kW, needs network operator approval before installation under the Energy Networks Association’s recommendations, and both systems sit above that in normal home configurations. Tesla rates four Powerwalls together at 44 kW, which is 11 kW each. We submit the G99 as soon as the design is agreed because it is the slowest part of the project.
Backup in a power cut
Both will keep the house running when the grid drops, with one difference in how you get there. SigenStor’s backup is part of the unit, with a 0 ms switchover. Powerwall 3 provides backup with the Backup Gateway 2; a Powerwall installed with the Remote Meter instead has no outage cover. That is the line item to check on any Powerwall quote, because the two configurations have different prices and the cheaper one does not do what most people assume a home battery does.
EV charging
SigenStor has an optional EV charger module that charges a car directly on DC from the battery and the panels, rather than through a separate wallbox. Powerwall pairs with a separate AC charger. Whether DC charging from the battery suits you depends on the car and how you drive; for many households a conventional 7 kW smart charger that charges from solar surplus is the simpler answer, with either battery. Our home EV charger installation page covers that choice.
Build, ingress and warranty
SigenStor’s enclosure is IP66; Powerwall 3’s is IP55 with IP67 ingress protection on the battery itself. Both are designed for outdoor mounting, which matters in the many West Midlands homes with no garage.
Both carry a 10-year warranty. Tesla’s terms are published in detail: 13.5 kWh at installation, 80% capacity retention at year ten for the UK, unlimited cycles for solar self-consumption, time-based control and backup, with other uses capped at 37.8 MWh of throughput. SigenStor’s product warranty is 10 years and the capacity retention terms are on the datasheet, which we attach to the quote rather than paraphrase.
Price: what is published and what is not
Tesla publishes UK hardware prices on its website: £5,000 for a Powerwall 3 without the Gateway and £5,975 with it, excluding VAT, delivery and installation. The installed price is higher and depends on the backup configuration, cable runs and the G99. Sigenergy publishes no UK list price; a SigenStor is priced by module count and inverter size on a fixed quote.
Two facts frame both. Installing a battery in a home is 0% VAT until 31 March 2027, after which it reverts to 5%. And the value of either battery is the gap between the price cap, 26.32p per kWh for October to December 2026, and what you would otherwise be paid to export, 12p per kWh on Octopus Outgoing Fixed, times the units the battery keeps at home.
Who installs it, and why that matters more for Tesla
Tesla’s UK warranty document, Rev. 1.16, effective 3 December 2025, applies to a Powerwall purchased from Tesla or a Tesla certified installer, and lists installation, commissioning or repair by anyone else as a ground for voiding the warranty. That makes the installer part of the product in a way it is not for most brands. Before you buy a Powerwall from any installer, including us, ask for their Tesla status in writing. We will answer that question directly; see our Tesla Powerwall installer page.
For both systems you also want MCS certification for battery storage, which is the certification export tariffs and insurers ask for. Green Tech Hub is MCS-certified for battery storage and solar PV through NICEIC (NIC-600049), and every battery we fit is installed to PAS 63100, the domestic fire-safety specification that BS 7671 Amendment 4 now requires.
Which one we would fit in your house
For a house installing solar and a battery together, with a roof of 3 to 6 kWp and an evening load that may grow, SigenStor: it fits now, it grows later, backup and the app are built in, and there is no installer condition on the warranty. Our Sigenergy installer page covers the details. For a household that specifically wants a single large unit, can use 13.5 kWh, and has checked the installer’s Tesla standing, Powerwall 3 is a very good battery. For a small roof with modest evening use, honestly, neither: a single 5 kWh unit such as the Duracell Dura5 will cost less and do the job. The survey decides, not the brochure, and our home battery storage page explains how we size one.
Sources
- SigenStor modules, stack limits, IP66, warranty, five-in-one description: Senergy Direct, Sigenergy SigenStor battery
- SigenStor 0 ms backup switchover: SigenStor Home datasheet (PDF)
- SigenStor inverter sizes: Wired by Jessops, SigenStor specifications
- Tesla Powerwall warranty terms and installer condition (European Warranty Region, Rev. 1.16): Tesla UK, Powerwall documents
- Tesla Powerwall UK pricing: Tesla UK, Powerwall order page
- Tesla Powerwall configuration, ingress ratings and Remote Meter note: Tesla UK, Powerwall
- G98 and G99 thresholds: Energy Networks Association, engineering documents
- PAS 63100 and BS 7671 Amendment 4: IET Wiring Matters
- 0% VAT on home battery installation to 31 March 2027: HMRC VAT Notice 708/6
- Ofgem price cap, 1 October to 31 December 2026: Ofgem energy price cap
- Octopus Outgoing export rates: Octopus Energy Outgoing