EcoFlow STREAM Ultra X
A 3.84 kWh balcony battery with a built-in micro-inverter and four MPPT inputs for 2,000 W of panels, expandable up to 23 kWh according to EcoFlow.
- Best for large solar storage
- Plug-in battery
- 3.84 kWh
- IP65
- Made by EcoFlow.
- Capacity: 3.84 kWh per unit, expandable from 3.84 to 23 kWh.
- Solar: 4 MPPT inputs for up to 2,000 W (4 x 500 W), up to 60 V.
- Power: 800 W grid-tied output, with up to 2,300 W off-grid.
- Rules: whether you can use it as a plug-in battery depends on your country.
Not tested by us
We have not tested the EcoFlow STREAM Ultra X. The figures on this page come from the sources listed at the end of the page, checked on 11 November 2026, and we do not show prices. "Best for" is based on what the maker says the product is designed for, not on our own tests.
Key figures
3.84 kWh
Per unit, up to 23 kWh
2,000 W
Solar input, 4 MPPT
10 years
Warranty
Specifications
Last checked on 11 November 2026. The grey text under each name explains what the value means.
| Specification | Value |
|---|---|
| Storage | |
| CapacityHow much energy the battery stores. Bigger means longer runtime or more of your own solar power used later. | 3.84 kWh per unit. EcoFlow says capacity can be expanded from 3.84 to 23 kWh. |
| Battery chemistryLFP (lithium iron phosphate) cells are known for long life and stable behaviour with heat. | Not stated on the product page |
| Cycle lifeHow many full charge and discharge cycles the cells are rated for before they hold less than the stated share of their original capacity. | 6,000 cycles to 70% capacity |
| ExpansionExtra battery units that add storage to the same system. | From 3.84 kWh up to 23 kWh, according to EcoFlow. The page does not list the expansion modules. |
| Power | |
| AC output, grid-connectedThe lower output allowed when it feeds power into the home's circuits or the grid. | 800 W grid-tied |
| Backup outputA separate socket that keeps selected devices running when the grid is down. | Off-grid AC output 1,200 W on the spec sheet, and the page says up to 2,300 W for high-demand appliances |
| AC charging inputHow fast it charges from a wall socket or the grid. | 1,200 W (10 A maximum) |
| Efficiency and standby useLosses when charging, discharging and doing nothing. | Not stated |
| Solar | |
| Solar inputsThe number of panel strings it can track separately (MPPT) and the total DC power. | 4 MPPT inputs, 2,000 W in total (4 × 500 W), maximum 60 V DC per input |
| Grid connectionThe supply type it is built for. Check it matches your home's supply. | Plug-in cables are not yet sold in the UK: EcoFlow says it ships with open-end cables and that plug-in cables will follow once new UK regulation takes effect. |
| Connection and housing | |
| Dimensions (W × D × H)Check the space before you buy, including room around it for airflow and cables. | 420 × 294 × 460 mm, as listed by EcoFlow (axis order not stated) |
| WeightMatters for lifting, wall mounting and moving it. | 38.8 kg |
| Protection ratingIP ratings show protection from dust and water. IP55 and IP65 are rated for outdoor-style exposure; check the installation guidance. | IP65 |
| Operating temperatureThe range it is rated to work in. Cold and heat can reduce performance. | -20 to 55 °C |
| Battery heatingA built-in heater that lets the battery charge in cold weather. | Self-heating battery, low-temperature charging activates at 5 °C or below |
| Noise levelFan noise while working. | Under 30 dB |
| ConnectivityHow you monitor and control it, usually through an app. | Wi-Fi and Bluetooth |
| Warranty | |
| WarrantyThe period the maker covers. Read the terms: conditions and capacity guarantees differ. | 10 years |
Compatible with
What EcoFlow says this product works with. Anything not listed here is not confirmed.
- Third-party devices
- EcoFlow says the STREAM series works with third-party devices that use Zigbee, Matter and Shelly protocols.
- Other STREAM products
- EcoFlow lists the STREAM AC Pro and STREAM batteries in bundles and for expansion.
Rules where you live
Rules for plug-in batteries differ by country. EcoFlow says plug-in solar regulation is expected in the UK in the coming months and that the STREAM series ships with open-end cables, with plug-in cables to follow. In Great Britain, plug-in solar kits of up to 800 VA have been legal since 27 August 2026, but the rules exclude plug-in batteries.
Check the rules, incentives and tariffs for your own country in our country guides.
Strengths and things to check
Strengths
- 3.84 kWh in one unit, expandable to 23 kWh
- Four MPPT inputs for up to 2,000 W of panels
- Up to 2,300 W of power for off-grid devices
- Self-heating battery and IP65
- 10-year warranty
Worth checking before you buy
- At 38.8 kg it is a heavy unit
- Whether it counts as a plug-in product depends on your country: check the rules below
- Grid-tied output is limited to 800 W
- The product page does not state the battery chemistry
Change log
We record changes to this page here, so you can see when figures such as the warranty were last updated.
- 11 November 2026
- Page published. Warranty at publication: 10 years (EcoFlow UK product page).
Where this information comes from
We have not tested the STREAM Ultra X. Every figure above comes from EcoFlow's UK product page for the STREAM Ultra X, last checked on 11 November 2026. A value this page does not state is shown as not stated. The page gives both 1,200 W and 2,300 W for off-grid output; we show both and the context EcoFlow gives.
We do not show prices, because they change often and differ between sellers.
- Manufacturer EcoFlow UK STREAM Ultra X page
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Common questions about EcoFlow STREAM Ultra X
Can I use the EcoFlow STREAM Ultra X as a plug-in battery in my country?
It depends on local rules. In Great Britain, plug-in solar kits up to 800 VA are legal since 27 August 2026 but the rules exclude plug-in batteries. EcoFlow ships the unit with open-end cables in the UK. Check our country guides.
How much solar can the STREAM Ultra X take?
EcoFlow lists four MPPT inputs and 2,000 W of solar input in total (4 × 500 W), up to 60 V DC.
How much can the STREAM Ultra X store?
One unit holds 3.84 kWh. EcoFlow says capacity can be expanded from 3.84 to 23 kWh.
Related guides
How much could a battery save you?
Our calculator uses your own usage and tariff to estimate what a home battery could save, with conservative assumptions.