Sigenergy vs Tesla Powerwall 3:
The Definitive UK 2025 Guide

Quick Verdict: Who should pick which – and why?

SUMMARY

Powerwall 3 = slick, powerful, integrated and battle-tested.

SigenStor = flexible, modular, feature-rich (including optional DC EV charging) and great for bespoke setups.

What’s Similar?

Both batteries represent excellent choices for UK homes and in fact they have quite a lot of strengths in common:

• LFP chemistry – safe and long-lasting
• 10-year warranties – peace of mind for a decade
• Grid-tied storage – enabling multiple grid applications
• Backup capability with islanding hardware – keep the lights on in a power-cut
• Smart-tariff control options, and modern apps – increased savings from your battery asset
• Both qualify for 0% VAT on residential installations (currently to 31 March 2027; retrofit batteries included from 1 February 2024)

Key Differences Explained

Despite the commonalities between the Tesla Powerwall 3 and Sigenergy SigenStor systems, they do differ in important ways:

Power & Backup Behaviour

• Powerwall 3 delivers up to 11.04 kW continuous AC per unit, with high surge capability (185 A LRA) for starting heavy loads – excellent for whole-home backup on a single phase when paired with Tesla Backup Gateway 2.
• SigenStor’s power depends on the Sigen Energy Controller size (e.g. 3-12 kW single-phase; 5-25 kW 3-phase), so you can right-size inverter power to your home and PV array. But, in contrast to the Powerwall, the SigenStor can offer backup power for both single- and 3-phase homes.

Capacity & Scalability

• Powerwall 3: 13.5 kWh per unit; stack up to 4 Powerwalls plus up to 3 Expansion Packs (total 94.5 kWh) and 44 kW AC continuous across four units.
• SigenStor: modular 5/6/8/10 kWh batteries per stack, multiple stacks in parallel; practical for garages/utility rooms where incremental additions are planned.

Solar Integration (DC/AC, MPPTs)

• Powerwall 3 includes a built-in solar inverter (3 MPPTs, up to 20 kW DC) – very tidy for new PV+storage installs, with fewer boxes on the wall.
• SigenStor is a hybrid platform; you choose controller size/MPPT count to match your array complexity.

Single- vs 3-Phase Homes

• Powerwall 3 is a single-phase device; on 3-phase supplies you typically install one unit per phase and manage the site with Backup Gateway 2 (which supports 3-phase sites).
• SigenStor offers native 3-phase controllers up to 25 kW, making it attractive for larger UK homes with 3-phase services or heat-pump-heavy loads.

Apps, Ecosystem & Smart Tariffs

• Tesla app is polished, with Storm Watch, Time-Based Control and Charge on Solar integrations.
• Sigenergy offers the mySigen app and, uniquely, an optional DC EV-charger module inside the same ecosystem – appealing if you want one vendor for PV, storage and EV charging.

Warranty & Degradation

• Powerwall 3: 10 years, 80% capacity at 10 years. In listed applications (solar self-consumption, time-based control, backup), cycles are unlimited; otherwise 37.8 MWh throughput applies. Internet connectivity is required to secure the full 10-year term.
• SigenStor: 10 years, 60% capacity at 10 years or throughput limit (e.g. 23.77 MWh for an 8 kWh module; 15.85 MWh for 5 kWh). There’s also an option to extend the warranty to 15 years (60% capacity).

Installation Practicalities (Space, Noise, Weather)

• Powerwall 3 is IP55 (wiring compartment IP55; battery & power electronics IP67) and can be wall or floor mounted; typical operating noise <50 dB. Dimensions 1105×609×193 mm.
• SigenStor is IP66 for outdoor installs without extra enclosures, helpful where indoor space is tight. The separate Gateway is IP54 which means it’s protected against dust and splashes of water – suitable for most sheltered, outdoor installations.

Bidirectional Charging

Bidirectional charging allows you to not only charge your electric vehicle but also use the energy stored in your car’s battery to power your home (Vehicle-to-Home, or V2H) or even send it back to the grid (Vehicle-to-Grid, or V2G).

• The Sigenergy SigenStor stands out with its fully integrated bidirectional EV DC charger (check your EV is compatible). This means the capability is built directly into their energy storage system, enabling seamless interaction between your home, solar panels, battery, and EV. This all-in-one approach simplifies the hardware required and allows for efficient use of solar energy to directly charge your vehicle.
• In contrast, while the Tesla Powerwall 3 has the hardware to support bidirectional charging, the feature is not yet enabled in the UK.

Real-World UK Considerations

Whatever battery storage you ultimately opt for, you need to bear in mind the following factors:

• DNO limits & paperwork: Exports above 3.68 kW per phase require a G99 application; smaller systems usually fall under G98 rules. Export limiting can be included in the design to avoid paperwork delays.
• Tariffs: Modern batteries can be set up for time-of-use charging and discharging as well as solar self-consumption. Always check that the battery’s app control matches your supplier’s requirements.

• 0% VAT: Residential installation of solar and battery storage – including retrofit – is zero-rated until 31 March 2027 in Great Britain. This gives households a significant saving on installed system prices.
• Placement & noise: Think about ventilation, waterproofing, and clearance before installation. Also factor in noise if locating near bedrooms or other habitable rooms.

Why Infinity Energy Services?