Tesla's Powerwall 3 and EcoFlow's PowerOcean dominate the 2026 UK home battery market, but they take fundamentally different approaches to the same problem.
The Powerwall 3 is built around tight ecosystem integration — one app for solar, battery, EV charging, and storm-aware backup. PowerOcean takes the modular route — start at 5 kWh, expand to 25 kWh in 5 kWh increments, with the longest warranty on the market.
We install both regularly. Five Tesla Powerwall 3 systems go in every week through our Salford depot, and PowerOcean has been the fastest-growing alternative since EcoFlow opened UK distribution in 2024.
Capacity and chemistry
Powerwall 3 ships at 13.5 kWh usable, expandable via 13.5 kWh add-on packs to 54 kWh total. Cell chemistry is LFP (lithium iron phosphate) since the late-2024 production run — the same chemistry as Tesla's Megapack utility-scale storage.
PowerOcean modules are 5 kWh each (LFP also), stacking to 5 modules per inverter for 25 kWh. Two inverter stacks deliver 50 kWh.
For most UK homes, 13.5 kWh is the sweet spot. A typical detached home with 4 kW of solar PV exports 70% of generation to grid without a battery; with 13.5 kWh of storage, that drops to 5–10%. Adding capacity beyond that returns rapidly diminishing financial value.
Warranty
This is where PowerOcean wins clearly: 15 years vs Powerwall 3's 10 years. Both warranty the system to retain at least 70% of original capacity.
In real-world terms, a 15-year warranty matters more than it sounds. By year 12 your battery has done about 4,000 cycles on a typical UK usage pattern. By year 15, 5,000+. Knowing it's still under warranty changes the maintenance calculus.
App and ecosystem
Tesla's app is genuinely better. It shows live power flow, lets you set time-of-use scheduling for Octopus Go / Cosy / Flux, and Storm Watch automatically tops the battery to 100% when the Met Office issues a storm warning.
EcoFlow's PowerInsight app is functional but rougher. Manual scheduling for off-peak charging, no automatic storm response.
If you also drive a Tesla, Powerwall integration with the Tesla app for solar-aware EV charging is a meaningful win.
Install and physical footprint
Powerwall 3 is wall-mounted indoor (normally a garage or utility) — 1.1m tall, 60cm wide, 19cm deep, 130 kg. Includes the 11.5 kW solar inverter, so for new solar installs you don't need a separate inverter.
PowerOcean is IP65 outdoor-rated. The inverter (separate unit) goes inside or out; battery modules stack outside. Saves indoor space, but you need a wall sheltered enough to host the modules.
Pricing in 2026
Like-for-like fitted prices through us: - Powerwall 3 with whole-home backup gateway: £8,400 fitted - PowerOcean 15 kWh stack: £8,200 fitted - Powerwall 3 + 4 kW solar bundle: £14,500 - PowerOcean 10 kWh + 4 kW solar bundle: £13,200
Which should you buy?
We'd steer you to Powerwall 3 if: - You're also fitting new solar (integrated inverter saves £900–£1,200) - You drive a Tesla - Indoor mounting space isn't a problem - Storm Watch backup matters (rural with poor grid reliability)
We'd steer you to PowerOcean if: - Adding to existing solar (AC-coupled, no inverter swap) - Outdoor install only option - You want to start at 5–10 kWh and expand later - 15-year warranty is the deciding factor
Either way, your installer should walk you through both options, show you a real PV*SOL or Aurora simulation of your specific roof and consumption pattern, and quote both before you commit.