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.