Marstek VENUS E Gen 3.0
A 5.12 kWh AC-coupled LiFePO4 battery that connects to your home with a single cable and works with an existing solar system.
- Best for existing solar
- AC battery
- 5.12 kWh
- 10-year warranty
- Capacity: 5.12 kWh nominal, with LiFePO4 cells. This is the VENUS E Gen 3.0, not the 2 kWh VENUS E Mini.
- Output: 800 W to the grid by default, up to 2.5 kW with local approval, and 2.5 kVA of backup power.
- Solar: AC-coupled, so it works alongside an existing on-grid solar system.
- Rules: whether you can use it as a plug-in battery depends on your country.
Not tested by us
We have not tested the Marstek VENUS E Gen 3.0. The figures on this page come from the sources listed at the end of the page, checked on 10 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
5.12 kWh
Nominal capacity
800 W
Default grid output (up to 2.5 kW with approval)
2.5 kVA
Rated backup output
Specifications
Last checked on 10 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. | 5.12 kWh nominal. About 4.61 kWh usable at 90% depth of discharge, before losses. |
| Battery chemistryLFP (lithium iron phosphate) cells are known for long life and stable behaviour with heat. | Lithium iron phosphate (LiFePO4) |
| 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. | Over 6,000 deep cycles at 80% capacity retention on the product page. Marstek's comparison article lists more than 10,000 cycles. |
| ExpansionExtra battery units that add storage to the same system. | Multiple units are supported. Marstek does not state a maximum on the pages we read. |
| Power | |
| AC output, grid-connectedThe lower output allowed when it feeds power into the home's circuits or the grid. | 800 W by default. Up to 2.5 kW continuous, which needs local utility or government approval. |
| Backup outputA separate socket that keeps selected devices running when the grid is down. | 2.5 kVA rated, and 3.5 kVA for 10 seconds, through a dedicated backup port |
| AC charging inputHow fast it charges from a wall socket or the grid. | 2.5 kW |
| Efficiency and standby useLosses when charging, discharging and doing nothing. | More than 93.5% battery-to-AC. Standby use is not stated. |
| Solar | |
| Solar inputHow much solar panel power it accepts. A higher figure fills the battery faster on a sunny day. | No separate solar input is stated. Marstek describes it as AC-coupled and compatible with existing on-grid solar systems. |
| Grid connectionThe supply type it is built for. Check it matches your home's supply. | AC-coupled, connected with a single cable |
| Connection and housing | |
| Dimensions (W × D × H)Check the space before you buy, including room around it for airflow and cables. | 480 × 153 × 624 mm, as listed by Marstek (axis order not stated) |
| WeightMatters for lifting, wall mounting and moving it. | About 60 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. | Stable operation down to -20 °C. The upper limit is not stated. |
| Noise levelFan noise while working. | Under 30 dB |
| ConnectivityHow you monitor and control it, usually through an app. | Dual RJ45 ports (RS485 and Ethernet), a LAN port and an open API for platforms such as Home Assistant and ioBroker. Wi-Fi and Bluetooth are not stated on the pages we read. |
| Warranty | |
| WarrantyThe period the maker covers. Read the terms: conditions and capacity guarantees differ. | 10 years |
Compatible with
What Marstek says this product works with. Anything not listed here is not confirmed.
- Existing solar systems
- Marstek says it is compatible with existing on-grid solar systems.
- Whole-home backup
- Supported with the optional Marstek Smart Box, for one unit or several in parallel.
- Home automation
- An open API supports platforms such as Home Assistant and ioBroker.
Rules where you live
Rules for plug-in batteries differ by country. Marstek's page says its default grid output of 800 W can be raised only with local utility or government approval, and we could not confirm a UK version or plug. 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
- 5.12 kWh in one unit, more than twice the VENUS E Mini
- 2.5 kVA of backup power through a dedicated port
- Works with an existing solar system
- IP65 and 10-year warranty
Worth checking before you buy
- Whether it counts as a plug-in product depends on your country: check the rules below
- Heavy at about 60 kg
- The default grid output is 800 W; more needs local approval
- Marstek's own pages give two different cycle-life figures
Change log
We record changes to this page here, so you can see when figures such as the warranty were last updated.
- 10 November 2026
- Page published. Warranty at publication: 10 years (Marstek product page).
Where this information comes from
We have not tested the VENUS E Gen 3.0. Every figure above comes from Marstek's product page and its VENUS E Mini versus VENUS E Gen 3.0 comparison article, last checked on 10 November 2026. Marstek's product page specification tab did not load as text, so we used the comparison article for capacity, size and weight. A value these pages do not state is shown as not stated.
We do not show prices, because they change often and differ between sellers.
- Manufacturer Marstek: VENUS E Mini vs VENUS E Gen 3.0 comparison
- Manufacturer Marstek VENUS E Gen 3.0 product page
Spotted an error?
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Common questions about Marstek VENUS E Gen 3.0
Can I use the Marstek VENUS E Gen 3.0 as a plug-in battery in my country?
It depends on local rules. Marstek says the default 800 W grid output can be raised only with local approval. In Great Britain, plug-in solar kits up to 800 VA are legal since 27 August 2026 but the rules exclude plug-in batteries. Check our country guides.
Which Marstek VENUS E is this page about?
The VENUS E Gen 3.0 with 5.12 kWh. Marstek also sells the VENUS E Mini with about 2 kWh, which we do not cover here.
Does the VENUS E Gen 3.0 have solar inputs?
Marstek does not list a solar input. It describes the unit as AC-coupled and compatible with existing on-grid solar systems, so it connects on the AC side of your home.
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