Battery Comparison · 2026

Tesla Powerwall 3 vs EcoFlow PowerOcean

Tesla Powerwall 3 and EcoFlow PowerOcean are the two best home batteries on the UK market in 2026. We install both — here's the head-to-head from a certified installer who fits 5 Powerwalls every week and is an authorised EcoFlow dealer.

Our verdict

For new solar installs go Powerwall 3 — the integrated 11.5 kW inverter saves £900–£1,200. For battery retrofits to existing solar, or anyone needing outdoor mounting, PowerOcean wins. PowerOcean's 15-year warranty is the longest in the market; if warranty matters most, that's the call.

Side by side

Spec by spec

Dimension	Tesla Powerwall 3	EcoFlow PowerOcean
Usable capacity	13.5 kWh (54 kWh stacked)	5–25 kWh modular
Continuous power output	11.5 kW	5 kW per unit
Cell chemistry	LFP	LFP
Warranty	10 years (70% capacity)	15 years (70% capacity)
Inverter included	Yes — 11.5 kW solar inverter	No (separate hybrid inverter required)
IP rating / mounting	IP67 — indoor or outdoor	IP65 — designed for outdoor
Backup mode	Whole-home with gateway	EPS auto-switch in 20 ms
Storm Watch / smart backup	Yes — Met Office API	Manual scheduling
App / monitoring	Tesla app — best in class	PowerInsight — functional
Price fitted (10–13.5 kWh)	£7,400 (battery only)	£7,200 (10 kWh)
Time-of-use tariff support	Octopus Flux/Go/Cosy/Intelligent	Octopus Flux/Go/Cosy
Installation time	6–8 hours	6–8 hours
UK stock availability (May 2026)	4–6 week wait typical	In stock through dealers

Best for Tesla Powerwall 3

New solar installs (integrated inverter saves £1k+)
Tesla EV owners (one app, app-aware EV charging)
Anyone in a poor-grid area (Storm Watch backup)
Indoor mounting space available
Whole-home backup gateway needs

Best for EcoFlow PowerOcean

Battery retrofits to existing solar (AC-coupled, no inverter swap)
Outdoor-only install (IP65 rated)
Modular expansion needs (5 kWh increments)
Longest warranty matters (15 yr vs 10 yr)
Smaller systems (5 kWh starting point)

Frequently asked

Common questions

Which is better for an existing 4 kW solar system?

EcoFlow PowerOcean — AC-coupled retrofit means no inverter swap. Powerwall 3 retrofit also works AC-coupled but you pay for the integrated inverter you don't need.

Which has the better app?

Tesla. Powerwall 3 integrates with the Tesla app showing live power flow, Storm Watch alerts, and TOU schedules. EcoFlow's PowerInsight is functional but rougher — manual scheduling, no automatic storm response.

Are both safe for indoor install?

Yes. Both use LFP chemistry with no thermal runaway risk. PowerOcean is IP65 (designed for outdoor) and Powerwall 3 is IP67 (rated for both). For UK utility rooms or garages either is fine.

Which holds resale value better?

Tesla — there's a stronger second-hand market, and Tesla rate of innovation means earlier units are still supported via firmware. EcoFlow is newer to the UK so resale market is thin.

We install both — get a quote

Free survey, fixed-price quote, MCS certified. We fit 5 Powerwalls every week and we're an authorised EcoFlow + GivEnergy dealer.

Get a Quote Call 0800 099 6606

Where to go next

For a modular battery that expands in 5kWh steps, EcoFlow PowerOcean.
For whole-home backup, Tesla Powerwall installation.
On the agricultural side, solar for farms and agricultural buildings.
On commercial systems, maintenance for commercial arrays.

Is your system worth upgrading? Find out free.

Tell us your postcode and what you have. A real engineer reviews it and comes back within one working day with an honest answer — including when the answer is "leave it alone".