Home battery storage is becoming increasingly accessible, with a new generation of systems promising simpler installation, intelligent energy management and greater control over household electricity use.
Two products attracting attention are the MARSTEK Venus E 3.0 and the EcoFlow DELTA Pro 3.
At first glance, they appear similar. Both use long-life LFP battery technology, both can be charged from the mains, both offer app-based control, and both can provide stored electricity when you need it.
However, there is an important difference.
The MARSTEK Venus E 3.0 is primarily designed as a home energy storage battery, while the EcoFlow DELTA Pro 3 is a powerful portable power station that can also be integrated into a wider home energy system.
That distinction makes each product better suited to a different type of customer.
The headline specifications
| MARSTEK Venus E 3.0 | EcoFlow DELTA Pro 3 | |
|---|---|---|
| Battery capacity | 5.12kWh | 4.096kWh |
| Battery chemistry | LiFePO₄ / LFP | LFP |
| AC output | Up to 2,500W | Up to 4,000W |
| Expandability | Up to 15.36kWh using 3 units | Up to 12kWh |
| Solar input | Designed primarily around AC-coupled home storage | Up to 2,600W direct solar input |
| App control | Yes | Yes |
| Smart energy management | Yes | Yes |
| Portability | Primarily stationary | Portable / wheeled |
| Weight | Approx. 60kg | 51.5kg |
| Weather protection | IP65 | Primarily suited to protected/indoor use |
| Primary purpose | Home energy storage | Portable power + home backup |
So which one makes more sense?
Where the MARSTEK Venus E 3.0 wins
1. More battery capacity as standard
Perhaps the biggest advantage of the Venus E 3.0 is straightforward: you get more energy storage in the base unit.
The MARSTEK provides 5.12kWh, compared with 4.096kWh in the EcoFlow DELTA Pro 3.
That's around 25% more nominal storage capacity.
For homeowners primarily buying a battery to shift electricity consumption — charging overnight on a cheap tariff or storing surplus solar generation and using it later — capacity can be more important than exceptionally high instantaneous output.
2. It is designed specifically to be a home battery
The Venus E 3.0 doesn't try to be a giant portable power station.
Its purpose is much simpler: store electricity and intelligently release it back into the home when required.
When paired with a compatible smart meter, the system can monitor household import and export and adjust charging and discharging accordingly.
For someone who already has rooftop solar, this is particularly attractive.
Rather than replacing an existing solar installation, the Venus can effectively sit alongside it as an AC-coupled battery.
3. Simple installation
One of the most interesting aspects of the Venus E is its plug-and-play architecture.
Unlike traditional home batteries that can require a dedicated hybrid inverter and significant electrical installation, the Venus has been designed to make adding storage considerably simpler.
That potentially makes home battery storage accessible to households that don't want the complexity and installation costs associated with a conventional fixed battery system.
4. Outdoor installation
The Venus E 3.0 carries an IP65 rating, giving it protection against dust and water.
That creates significantly more flexibility when deciding where to locate a large battery.
Garages, utility areas and suitable outdoor locations can all become possibilities where installation conditions allow.
5. Built around energy arbitrage
The MARSTEK app allows owners to schedule charging and discharging.
That means households on tariffs offering cheaper overnight electricity can charge the battery when electricity is inexpensive and use that stored electricity during more expensive periods.
For many UK households, this may actually be the primary financial argument for buying a home battery.
Where the EcoFlow DELTA Pro 3 wins
The comparison isn't one-sided.
There are several areas where the DELTA Pro 3 is clearly the more capable machine.
1. Much greater power output
This is probably the biggest EcoFlow advantage.
The DELTA Pro 3 can provide up to 4,000W of AC output, compared with 2,500W from a single Venus E 3.0.
That makes a significant difference if you want to run demanding appliances.
Kettles, ovens, heaters, washing machines and other high-power devices can quickly push household demand above 2.5kW.
For pure backup-power capability, the EcoFlow therefore has the advantage.
2. Direct solar input
The EcoFlow also has another substantial advantage: solar panels can be connected directly to it.
The DELTA Pro 3 accepts up to 2,600W of solar input across two PV inputs.
That makes it particularly attractive for cabins, motorhomes, workshops and off-grid installations where a conventional grid-connected solar inverter may not already exist.
The MARSTEK makes more sense when you're adding battery storage to an existing household electricity or solar system.
3. It's genuinely portable
Neither battery is something you're going to carry around casually, but EcoFlow has made the DELTA Pro 3 transportable.
At around 51.5kg, it incorporates wheels and can be moved between locations.
The Venus E 3.0 weighs around 60kg and is much more obviously intended to remain in one place.
For someone wanting one battery that can serve the house, a motorhome, workshop or off-grid location, the EcoFlow is the more versatile option.
4. More outputs
The DELTA Pro 3 is effectively an enormous power station.
Alongside its AC outlets, it provides USB-A, USB-C, 12V DC and Anderson connections.
That means devices can be powered directly from the battery without first feeding electricity into a home's electrical system.
For emergency preparedness, camping or mobile use, that's a major advantage.
5. A broader ecosystem
EcoFlow has developed an extensive ecosystem around its batteries.
The DELTA Pro 3 can work with additional batteries, solar panels, alternator charging, generators and other EcoFlow accessories.
For customers who want to build a more complex off-grid or backup system over time, that ecosystem is a compelling reason to choose EcoFlow.
Where MARSTEK's simplicity becomes its advantage
The EcoFlow's versatility is impressive, but there's another way of looking at it.
If your objective is simply:
“I want a battery for my house.”
…many of the DELTA Pro 3's capabilities may not be particularly important.
You may never use its USB ports.
You may never put it in a vehicle.
You may never connect portable solar panels directly to it.
And you may never need 4,000W from the battery itself.
For that customer, the Venus E 3.0's simplicity starts to make considerably more sense.
You're buying a 5.12kWh home battery, rather than a portable power station that can also perform home-energy duties.
Where EcoFlow's extra power matters
There is an important caveat.
A 2,500W output limit means the Venus E 3.0 cannot necessarily cover every electrical load in a typical house simultaneously.
Imagine the battery is supplying:
- a 2,000W kettle,
- a 500W background household load,
- and somebody turns on another high-powered appliance.
You've already reached the output capability of a single Venus.
EcoFlow's 4,000W output provides substantially more headroom.
So customers particularly concerned about high-power backup during a blackout may find the DELTA Pro 3 more suitable.
MARSTEK partly addresses this through expansion: multiple Venus E 3.0 units can increase both storage capacity and available output.
Solar owners should think carefully about the difference
This is where the choice becomes particularly interesting.
If you already have rooftop solar, the MARSTEK approach can be very attractive.
Your existing solar inverter continues doing its job. The battery monitors what the house is importing or exporting and stores surplus electricity for later use.
There's no need to buy another set of solar panels specifically for the battery.
If you don't already have solar and want to build a portable or off-grid solar system from scratch, the EcoFlow's integrated MPPT solar inputs give it a clear advantage.
The right product therefore depends heavily on the system around it.
Which one would we choose?
For dedicated household energy storage, the MARSTEK Venus E 3.0 is arguably the more focused proposition.
Its 5.12kWh capacity, smart-meter integration, weather-resistant enclosure and home-energy-focused design make it particularly interesting for households wanting to store solar generation or take advantage of time-of-use electricity tariffs.
For backup power, off-grid use and portability, the EcoFlow DELTA Pro 3 is the more capable machine.
Its 4,000W AC output, direct 2,600W solar input, extensive selection of outputs and portable design give it capabilities that the Venus E isn't trying to replicate.
Choose the MARSTEK Venus E 3.0 if:
You primarily want to reduce household electricity costs, add storage to an existing solar installation, charge cheaply overnight and discharge during expensive periods, or simply want a large dedicated home battery without installing a conventional hybrid battery system.
Choose the EcoFlow DELTA Pro 3 if:
You need significantly higher AC output, want direct solar charging, expect to move the battery between locations, need numerous AC/DC/USB outputs, or want a system equally suited to home backup and off-grid use.
The verdict
There isn't really a universal winner because these two batteries approach energy storage from opposite directions.
EcoFlow has built a highly capable portable power station that can become part of a home energy system.
MARSTEK has built a home energy storage system and made it almost as simple to use as a portable power station.
For many homeowners, that distinction is more important than any individual specification.
If the objective is maximum versatility and power, EcoFlow wins.
If the objective is straightforward, high-capacity household energy storage, MARSTEK makes a very compelling case.
And as plug-and-play battery technology continues to develop, products such as these could dramatically change how UK households think about storing and using their own electricity.
