Tesla Powerwall 3 against the alternatives, and where each one wins

The short answer

The Powerwall 3 stores 13.5 kWh, discharges at up to 11.04 kW, and has the solar inverter built into it, so on a new solar installation one unit does the job that used to take two boxes on the wall. That combination of power and integration is genuinely hard to match. What it will not do is arrive in smaller pieces, keep your lights on without extra hardware, or bolt onto a Powerwall 2 you already own, and for a lot of UK houses those three limits matter more than the headline power figure.

What the Powerwall 3 actually gives you

The integration is the real product. Panels wire straight into the unit across three separate maximum power point trackers, up to 20 kW of solar at standard test conditions, so there is no second inverter on the wall and one less warranty to chase. Tesla's UK datasheet puts solar going to your home or the grid at 97.5 per cent, and solar routed through the battery first at 89 per cent.

Source: Tesla Powerwall 3 datasheet, United Kingdom edition, certified to G98, G99 and G100, checked 20 August 2026. Higher continuous output figures for this product circulate widely online. They are taken from the American split phase edition of the datasheet and do not describe a UK installation.

That output setting is not a detail. Your installation team sets it to suit your grid connection, and the 3.68 kW step decides whether the job goes in under a simple notification or needs permission before work starts. Our guide to G98 and G99 covers what changes on either side of that line.

Four things that count against it

• Capacity comes in 13.5 kWh steps. There is no 8 kWh Powerwall and no half unit. If your evening use lands at 9 kWh you buy 13.5 kWh, and if it lands at 16 kWh the next step is 27 kWh with an Expansion unit. Tesla supports up to three Expansion units per Powerwall and four Powerwall 3 units in total, so the ceiling is high and the granularity is coarse.
• Backup needs a Backup Gateway 2. The datasheet lists it as the supported islanding device, and Tesla's UK support pages confirm a Gateway is installed with a Powerwall 3 as it was with a Powerwall 2. It is separate hardware with its own labour and its own consumer unit work, and it is the most common surprise on a battery quote. Ask for it as its own line.
• It charges at half the rate it discharges. Up to 11.04 kW out, up to 5 kW in. On a five hour off peak window that is no constraint for one unit, since 13.5 kWh at 5 kW fills in about two hours forty minutes. It bites on a 27 kWh system, on tariffs giving you several short windows rather than one long one, and when you want to grab a sudden burst of midday sun.
• It cannot be added to a Powerwall 2. Tesla's UK support page is unambiguous: a Powerwall 3 can be added to other Powerwall 3 batteries but not to a Powerwall 2. Tesla Australia now publishes the opposite, having enabled backwards compatibility through a software update, so this rule is moving. If you already own a Powerwall 2, get the current UK position confirmed in writing before anyone surveys your house.

The higher capacity, lower power alternative

The Duracell Dura16 LV is the clearest counterpoint in the UK market. It holds 16 kWh with 14.4 kWh usable, which is more storage than a Powerwall 3, and moves it at 6.6 kW, which is a good deal less. It uses lithium iron phosphate cells rated for 8,000 cycles in a fanless IP65 case weighing 122 kg, carries a ten year warranty, and supports up to twelve units in parallel. It is made and warranty backed by Puredrive Energy in Toddington, Gloucestershire, under licence to the Duracell name.

The catch is structural rather than technical. The Dura16 is a battery, not a system, so it needs a separate hybrid inverter beside it, and that inverter sets the real charge and discharge ceiling rather than the 6.6 kW on the battery datasheet. On a new solar installation that is a genuine disadvantage against the Powerwall. On a retrofit to solar you already own, where the Powerwall's built in inverter sits unused anyway, it stops being a disadvantage at all.

Sources: Tesla Powerwall 3 datasheet, United Kingdom edition, and the Duracell Energy Dura16 LV datasheet v1.2 for model PD-16KWH-50V-1G, both checked 20 August 2026. The Dura16 charges and discharges at up to 130 A, which is 6.6 kW at its 51.2 V nominal voltage.

Read that for the shape rather than the winner. The Powerwall gives you nearly twice the power and a simpler installation. The Dura16 gives you slightly more energy, a faster fill on a short cheap window, and the option to size the inverter separately from the storage. Full detail sits on our Tesla Powerwall 3 and Duracell Dura16 pages.

Modular systems, and what the granularity buys

The third approach abandons the single large unit. The Enphase IQ Battery 5P is the clearest example sold in Great Britain: 5.0 kWh usable per unit, 3.2 kVA of continuous output, six microinverters embedded in each battery so the whole thing is AC coupled, a stated AC round trip efficiency of 90 per cent, and 78.9 kg installed. The warranty is where this approach makes its strongest case, covering above 60 per cent of capacity for up to fifteen years or 6,000 cycles, whichever comes first, against Tesla's ten year term.

The cost of that granularity is unit count. Matching a single Powerwall 3 on energy takes three IQ Battery 5P units, and even then combined output sits below 10 kVA. You get three sets of fixings, three cable runs and three prices against one box that does everything. What you gain is the ability to buy 5 kWh now and 5 kWh in three years, to spread weight across a wall that cannot take 130 kg in one place, and to lose only a third of your storage if a unit fails.

The efficiency figures across these three products are not directly comparable and are not a league table. Tesla publishes 89 per cent for solar routed through the battery and 97.5 per cent for solar passing straight through, on a weighted test methodology. Enphase publishes 90 per cent AC round trip at half power and 25 degrees. Different measurement bases, different answers.

Which system suits which house

On price, our package is from £6,350 installed for the 13.5 kWh Powerwall 3 and £10,850 for the 27 kWh setup with an Expansion unit, against £4,450 installed for a Dura16 alongside solar panels and £8,900 for two of them. Those two sets of numbers are not like for like: the Duracell prices are specifically for a battery fitted with a solar array, while the Powerwall figure is a battery package. A battery only price for either is confirmed on your call rather than published as a number we would immediately have to qualify.

What to get in writing before you sign

1. The output setting in kW, and whether the job goes in as a G98 notification or a G99 application. That decides your timeline more than anything else on the quote.
2. The Gateway, or its equivalent, itemised separately with its own labour, or a written statement that the system will not provide backup.
3. The charge power as well as the discharge power, alongside the length of the cheap window on the tariff you intend to use. Octopus Go, for instance, runs 00:30 to 05:30.
4. The retained capacity percentage at the end of the warranty term, not just the number of years, plus any condition attached such as an internet connection.
5. For a battery that needs one, the exact make and model of the hybrid inverter and its own warranty term, since it sets the real limits of the system.

Clearline never installs anything. Work is carried out by an MCS-certified installation team for your area, and our job is to tell you which of these systems fits your house before a salesperson tells you which one is on offer this month. Our battery storage hub covers the wider picture, what a battery costs in 2026 covers the money, and what happens when a manufacturer fails covers the risk nobody prices in.

Specifications checked against the manufacturers' own datasheets on 20 August 2026: Tesla Powerwall 3, United Kingdom edition; Duracell Energy Dura16 LV v1.2; Enphase IQ Battery 5P, Great Britain edition. Package prices are Clearline's own, published on our product pages the same date and subject to survey. Tesla, Powerwall, Duracell and Enphase are trademarks of their respective owners. Clearline is an independent guidance service, is not affiliated with or endorsed by any of them, and holds no manufacturer accreditation.