Marstek Venus E 3.0
(9 reviews)
The plug and play solar battery that couples to your existing PV system: 5.12 kWh expandable to 15.36 kWh, 2.5 kW output, AI powered.
Characteristics
- Capacity: 5120 Wh LiFePO4, expandable to 15.36 kWh
- Power: 2.5 kW bidirectional, backup 2.5 kVA (3.5 kVA peak)
- Efficiency: Battery to AC efficiency > 93.5%, over 6000 cycles
- Rating: IP65, -20 °C to +55 °C, 60 kg
- AI mode with dynamic tariffs, up to £1,150/year in savings
Detailed overview: Marstek AC-coupled solar battery, 5.12 kWh
The Marstek Venus E 3.0 (Gen 3.0) is an AC-coupled home battery designed for households that already own solar panels and an inverter. Unlike a standard solar kit, it replaces nothing: simply plug it into a dedicated mains socket to start storing energy from the existing system, with no work on the wiring or the inverter.
Its native 5120 Wh capacity relies on LiFePO4 cells rated for over 6000 cycles at 90% depth of discharge, an estimated 15-year lifespan backed by a 10-year manufacturer warranty. AC power reaches 2.5 kW on input and in premium output mode (0.8 kW in the default configuration), with a stated battery-to-AC efficiency above 93.5%. Up to three units can be combined in single-phase setups to reach 15.36 kWh and 7.5 kW.
A dedicated backup output delivers up to 2.5 kVA continuously (3.5 kVA peak for 10 seconds), enough to keep lighting, a router or a fridge running during a power cut. Paired with the CT002 smart meter, zero feed-in mode prevents any surplus solar power from being exported to the grid, useful in regions with limited or poorly compensated feed-in.
Control runs through the Marstek app, with three selectable modes: AI optimisation, self-consumption or manual. AI mode automatically schedules charging cycles around dynamic electricity tariffs (including Nord Pool, Tibber and Octopus Energy), for annual savings advertised up to £1,150 based on two full cycles per day. The battery communicates over WiFi, Bluetooth and RS485, with an open API compatible with Home Assistant and ioBroker.
The fanless, naturally convection-cooled casing stays quiet (under 30 dB) and is IP65 rated, for reliable operation from -20 °C to +55 °C, indoors or in a sheltered outdoor spot. At 60 kg and 480 x 153 x 624 mm, installation is a one-person job. One drawback noted by several users: some electricity suppliers are still missing from the AI mode list, which then requires manual scheduling until they are added.
Full specifications
Detailed characteristics
Battery
| Technology?Battery chemistry; LiFePO4 lasts far longer and can be fully discharged, gel/AGM is maintenance-free and cheaper. | LiFePO4 (lithium) |
|---|---|
| Nominal voltage?Battery voltage (12, 24 or 48 V). | 51.2 V |
| Capacity?Capacity in amp-hours; multiply by voltage to get energy in Wh. | 100 Ah |
| Energy?Stored energy in watt-hours. | 5120 Wh |
| Cycle life?Rated number of charge/discharge cycles, at the stated depth of discharge. | 6000 cycles (90 %) |
| Expandable up to?Maximum capacity reachable with add-on modules. | 15360 Wh |
Power and protection
| Output power?Maximum power delivered (for storages with a 230 V output). | 2500 W |
|---|---|
| Built-in BMS?Battery management system protecting against overcharge, deep discharge, short-circuit and overcurrent (lithium batteries). | Yes |
| Low-temperature protection / heating?Cuts off or heats charging in cold weather to protect the lithium cells. | Yes |
Solar section
| Micro-inverter?Power of the inverter that feeds energy back into the home grid. | 2500 W |
|---|
Connectivity
| Bluetooth?Monitoring and settings via an app over Bluetooth. | Yes |
|---|---|
| Wi-Fi?Remote control and updates over Wi-Fi. | Yes |
Durability and format
| Ingress protection?Water and dust resistance (IP rating). | IP65 |
|---|---|
| Maintenance-free?Sealed battery needing no water top-up (gel / AGM). | Yes |
| Weight?Weight of the battery. | 60 kg |
| Dimensions (L × W × H)?Length × width × height, in millimetres. | 480 × 153 × 624 mm |
Availability and warranty
| Market launch?Date the model first became available on the European market. Useful to place its generation: technology moves fast in this segment, and a device several years old may be at the end of its commercial life. | August 2025 |
|---|---|
| Warranty?Length of the manufacturer's warranty. | 10 years |
Comparison
Around £1,000 to £1,400, the Marstek Venus E 3.0 competes with several plug and play solar batteries searched via queries like "Venus E 3.0 vs Solarbank 4" or "Marstek vs Bluetti Balco". Here is how it compares to three alternatives of similar capacity: the Anker Solix Solarbank 4 E5000 Pro, the Bluetti Balco 500, both around 5 kWh, and the Zendure SolarFlow 3000 Mix AC+, more powerful and more expensive.
| Criterion | Marstek Venus E 3.0 | Anker Solix Solarbank 4 E5000 Pro | Bluetti Balco 500 | Zendure SolarFlow 3000 Mix AC+ |
|---|---|---|---|---|
| Capacity | 5120 Wh, expandable to 15.36 kWh | 5024 Wh, expandable to 30 kWh | 5024 Wh, expandable to 30 kWh | 8000 Wh, not expandable |
| AC power | 2.5 kW bidirectional | 2.5 kW output | 3.68 kW output | 3 kW bidirectional |
| Battery chemistry | LiFePO4 | LiFePO4 | LiFePO4 | LiFePO4 |
| Weight | 60 kg | not stated | ≈ 63 kg | ≈ 80 kg |
| Observed price | £1,399 | ≈ £1,650 | ≈ £1,390 | ≈ £1,730 |
Overall, the Marstek Venus E 3.0 stands out for the best price-to-capacity ratio in this comparison, with near-identical capacity to the Anker Solix Solarbank 4 E5000 Pro and the Bluetti Balco 500 at a noticeably lower price. The Bluetti Balco 500 wins on continuous output power, and the Zendure SolarFlow 3000 Mix AC+ keeps the edge on raw capacity, but with a much heavier unit and a considerably higher price.
Related video
Video: Marstek Venus-E GEN 3.0 - Brandaktueller Energiespeicher im Test! - Published on 26/08/2025
Our tester's review: Julien De Jurquet
On paper, the Venus E 3.0's promise fits in one sentence: plug it in and gain solar autonomy without touching the rest of your setup. In practice, that is exactly what happens. The unit sits on the floor or wall-mounts in minutes, the Marstek app detects it instantly, and manual mode works flawlessly from the first connection. User feedback confirms this simplicity, with one recurring caveat: AI mode stays limited until your own electricity supplier is recognised in the app, which sometimes forces manual scheduling in the meantime. The advertised 93.5% efficiency drops a little in real use, between charge and discharge losses, something few manufacturers state as openly. The quiet operation and the sturdiness of the aluminium casing are widely praised. For a household that already has solar installed, it is a simple and affordable way to boost self-consumption without major work.
Frequently asked questions: Marstek AC-coupled solar battery, 5.12 kWh
No, the Venus E 3.0 is an AC-coupled battery: it plugs in downstream of a photovoltaic system that already has an inverter, with no built-in MPPT. It is not meant as a first solar setup, but as an addition to an existing installation.
Prices seen in early 2026 range roughly from £1,000 to £1,400 for the single 5.12 kWh unit depending on the retailer, with regular promotions. Expect more for the version bundled with the CT002 smart meter.
By combining up to three units in a single-phase setup, total capacity reaches 15.36 kWh with a combined 7.5 kW of power, enough to cover a household with higher consumption.
The dedicated backup output delivers up to 2.5 kVA continuously (3.5 kVA peak for 10 seconds), enough to keep lighting, a router or a fridge running until power returns.
Marstek advertises savings of up to £1,150 a year based on two full cycles per day, depending on local electricity tariffs and sunshine. This figure remains an estimate to check against your own consumption.
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Published on 24/08/2026