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Marstek Venus D Expansion Battery
Marstek Venus D Expansion Battery

Marstek Venus D Expansion Battery

Sale price€799,00 Regular price€899,00

Free shipping in mainland Spain, Portugal and Balearic Islands

The expansion batteries of the Marstek Venus D allow you to increase the storage capacity of your solar system quickly and easily.

 

Each expansion battery adds 2.56 kWh and you can stack up to 6 units to reach a total of 15.36 kWh without any modifications or construction work.

  • Direct integration with the main Marstek Venus D unit
  • Supports up to 8 solar panels connected
  • Handles up to 4 kW of solar input with 4 MPPT
  • Provides up to 2200 W of output for home consumption
  • Includes backup mode for power outages
  • Compatible with Smart Meter and Smart Box

Increase the autonomy and self consumption of your solar system.

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Questions? Call or text +34 640 91 31 51
Marstek Venus D Expansion Battery
Marstek Venus D Expansion Battery Sale price€799,00 Regular price€899,00

Marstek Venus D

Marstek Venus D installation video

A whopping 4 kW of solar input

Maximize your energy independence

Maximize your energy independence

Connect up to 8 solar panels directly

Connect up to 8 solar panels directly through the 4 MPPT integrated into the main unit, for a maximum of 4 kW of solar input. The main unit includes the micro inverter and controller.

Use all your surplus solar production

If you already have a solar kit installed, store your energy surplus through your home network. You do not need to connect the panels directly. With the help of the Smart Meter, the battery charges even if it is plugged into another outlet in your home.

Charge from the grid when the price is lower

Even if you do not have a solar installation, you can still reduce your power bill. Charge your battery during the hours when electricity prices are lower and use that energy when you need it most.

Over 15 kWh of modular storage

Modular storage keeps your home powered

Modular storage keeps your home powered

Stack up to 6 expansion batteries

You can reach up to 15,36 kWh of storage by stacking 6 expansion batteries of 2,56 kWh each in just minutes. No modifications or construction work are required.

Increase your storage at your own pace

You do not need to make the full investment from the beginning. Start with the main unit and a single expansion battery, and increase your storage according to your consumption and needs.

Solar energy through the night

With up to 15,36 kWh of storage capacity, you can keep your devices running day and night with solar energy, without consuming from the grid.

2.200 W of continuous power output with outage protection

All the power you need to keep your home running

All the power you need to keep your home running

Output power

With 2.200 W of output, the Marstek Venus D provides the power you need to maximize your savings, power your home and keep using solar energy at night.

Backup for power outages

The Marstek Venus D provides backup during outages through its AC output, where you can connect your essential devices and keep them running during a blackout.

Zero discharge with the Marstek Smart Meter

Avoid sending your surplus solar production to the public grid. The Marstek Smart Meter monitors real time consumption and helps the battery decide when to store, release or stop energy production for maximum efficiency.

Data sheet

The Marstek Venus D takes your self consumption to the next level with smart technology

Capture and use every W without waste

Capture and use every W without waste

Maximize your savings intelligently

With the Marstek Smart Meter, you make better use of your solar production, optimize your energy consumption and reduce your electricity bill. Everything is managed automatically and truly intelligently.

Monitor your energy

Track your production, consumption, storage and savings through the Marstek mobile app. Choose between self consumption mode, AI mode, manual control or outage backup, all with a single tap on your phone.


🔗 Marstek App Google Play
🔗Marstek App Apple

Product FAQs

Storage

How does a storage system for my plugin solar kit work?

How does a storage system for my plugin solar kit work?

In short: as easy as a plugin solar kit.

There are different types of storage systems, can be divided into these main categories:

  • Storage for already installed plugin solar kits. If you already have a plugin solar kit with solar panels and a micro inverter installed, you can add a storage system between your solar panels and the micro inverter. These systems are generally very easy to install, and in some cases (like the Saturn C B2500) even expandable in a modular way.
  • All-in-one storage systems. If you want to add storage to your first plugin solar kit, an all-in-one solution is best. These systems combine batteries, controllers and micro inverters into a single system. You plug the solar panels in on one side, and connect the system straight to your home socket on the other.
  • Standalone storage systems. Recently a third category of storage systems has launched, that doesn’t need a direct connection to your solar panels or plugin solar kit. These independent storage systems connect to any household plug, and store all surplus power your solar kit produces. They charge and discharge through your home’s electricity network, and can also be charged with grid energy if you want to top up in low-cost times or have no solar installed at all.

Can I also charge my storage with power from the grid?

Can I also charge my storage with power from the grid?

In short: with a hybrid storage system, yes.

Most storage systems that have launched in recent months include “hybrid” charging. This means that the storage system can not only discharge into the home’s power network, but also charge from it. This functionality allows you to top up your battery with power from the grid. This makes sense if your power tariff has very cheap prices in some dayparts, when topping up costs little, and use that power in the more expensive dayparts.

How much storage do I need for my home?

How much storage do I need for my home?

In short: this depends on your consumption levels.

Storage needs can be looked at from several sides:

  • Solar kit production. If you look at how much your solar kit produces during an entire day, and how much you consume on the spot, the rest is what you will have to store. For example, if your Plus 2000 kit produces 8 kWh per day but during the day you only use 3 kWh, then you need at least 5 kWh of storage for your surplus, to use it when the sun doesn’t shine.
  • Household demand. If you know how much you consume per day at home after subtracting the immediate consumption of your solar kit’s production, you know what you're missing. A part of that can be covered by storing your solar kit’s surplus. The rest can be covered by charging in low-cost hours from the grid. For example, if you consume 10 kWh per day in the above example, you will need 2 kWh to charge from the grid on top of the 5 kWh mentioned above.

And remember, that when it comes to batteries, you should never discharge below 10% and never charge over 90%. This means that you can only use 80% of any battery capacity. This would mean that in the above scenario of 7 kWh of required storage, you will need a storage system of 9 kWh, whose 80%-capacity of 7,2 kWh covers your needs.

Will a storage system also work during power outages?

Will a storage system also work during power outages?

In short: Some of them do.

Several storage systems that have launched recently have an “AC outlet”, also known as “emergency outlet” or “anti-blackout”. This is a Schuko socket that delivers electricity when the network goes down. These systems can also be used in homes that are not grid connected.

During power outages, like the “apagón” in Spain, Portugal and parts of France in April 2025, these systems provide critical base power to their customers, literally “keeping the lights on”. With sufficient storage capacity, and daily recharge with your solar kit, you can easily get through power outages also for longer periods of time.

Does a storage system store all my surplus energy?

Does a storage system store all my surplus energy?

In short: yes it can.

For any storage system to work effectively, or be “intelligent” as sometimes labelled, you need a smart meter. This device measures the flow of electricity from the grid to your home.

If you consume from the grid, it will tell your storage system to feed in more, trying to reduce or eliminate grid consumption.

If you feed surplus energy into the grid, it will tell your storage system to store that surplus energy. These changes happen in real time in fractions of a second, and maximize the self consumption of your solar energy. Since you don’t feed into the grid you’re also not subject to certification or registration requirements in many countries.

What our customers say about us

Daniel

Excellent service

The entire process went smoothly. The website is simple and effective. The payment process was transparent and seamless. The shipment was on time, although the carrier split it into two packages with only one tracking number, which caused some confusion for me, but this was quickly clarified by Robinsun's customer service.

Rafael

Excellent customer service

Excellent customer service, fast shipping and quality product at a good price.

Marstek Venus E 3.0 - 5.12 kWh

Jose Antonio Granero Miralles

Everything perfect

The personal service over the phone was outstanding. There was a problem with the agency, and they resolved it quickly. I will work with them again and recommend them.

Harry O'Connor

Amazing support and great prices

Amazing support and great prices. What's not to like? Really lovely people on WhatsApp helping you with everything. Don't delay, invest in solar!

Marstek Venus E 3.0 - 5.12 kWh

Benz Kotzen

Delivering to us in Portugal is difficult and despite the difficulties with the Portuguese postal system, the staff at Robinsun were extremely helpful. The plug and play system we ordered was delivered within the set time frame, all pieces present and well packaged and now we are getting the 800 kWh at peak sun as promised.

Paul Brabant

Get your equipment here

I only have good things to say about this company. I haven't experienced customer like this in Spain. Reminds me of the best companies in the US, where the customer is king. Super easy installation, quick software install, and up to 1.3kwh with 4 panels. Brilliant.

Wies Verstraete

The service of Robinsun is outstanding

The service of Robinsun is outstanding. Although the panels were damaged in the transport (which wasn't their fault), they did everything to send new panels asap. Very easy communication via WhatsApp.

Pedro Oliveira

Overall experience was pretty good with a package that made sense, good videos explaining how to set everything up and follow up over whatsapp to confirm everything was going as expected.

IZ0 JUB

5 Star After Sales Service

I would like to thank Boris and his team for swapping out the TSUN storage battery for the ANKER Solarbank through no fault of Robinsun's the manufacturers TSUN admitted there was a problem with their equipment. The Anker is working great and giving us power all through the evening and is usually fully charged at this time of the year just after lunch. Robinsun's after sales service is second to none. 5 stars plus.

Anker Solarbank E1600

Eduard Frades Fabrega

I bought a basic setup without issues…

I bought a basic setup without issues and I got am excelllent support before buy the product.

Moisés

The experience is very positive, they are giving you support for all the problems that you can suffer, for example, logistic, configuration. To me they are the best.

Luis Gomes

Excelent products and excelent support.

Excellent products and excellent customer support. I bought a solar kit, and from the very first moment, the support via WhatsApp was excellent. Very fast delivery to Portugal without any problems. Everything worked perfectly, and I was very satisfied. I recommend Robinsun and will buy from this company again in the future.

Marco Mendes

Very good customer service

Very good customer service! Would definitely buy again from Robinsun!

Celso Vieira

Customer support is great. Instalation was very easy and fast. In no time it was working, producing power and saving the planet. Recommend to all. Good job robinsun!

Ulrich S Barcelona

This is a very simple fast and economic way…

...to start producing solar energy by yourself in Spain. Very responsive, and smooth and fast shipment and declaration to the authorities. Very easy to assemble.

City 800

Paolo Tedone

Excellent customer service

Excellent customer service, fast, reliable.
Product according to description, easier than IKEA to install.
From 10am 100% coverage of baseload needs, when sunny 😉

António Olaio

Excellent customer service

Excellent customer service. Always available and with clear and accurate information. Received the order the next day, well before the expected delivery date. 5 well-deserved stars.

Marstek Saturn C - B2500

Jose Antonio

Friendly service and quality materials

Very fast shipping and everything perfectly packaged. The system's anchors are high quality. The system itself is working correctly. The information and advice provided beforehand were very helpful and accurate.

Lydia C

Excellent personalized service

The team guided me through the process of choosing my kit; I didn't know anything and they explained everything to me. Highly recommended.

Marstek Venus E 3.0 - 5.12 kWh

Marc Borràs Conte

Everything was great!

The purchase process went very well. They answered all my questions both before and after the purchase. Excellent!

City 800

Juan Carlos Alguacil

Professional and friendly supplier

The purchase arrived on the expected date. I had some setup issues that the manufacturer resolved with an update. The after-sales service and customer support were friendly and prompt.

Marstek Jupiter C Plus

Miguel Angel Pastor Colinas

Excellent service

Excellent service, advice, and now installation follow-up. For the small amount I purchased, they've been very helpful. I hope to expand my installation with them.

Mary Aranda

City 800 Pack Highly Recommended

I bought the City 800 pack and it works great. It's easy to install and doesn't require any advanced DIY skills. I recommend it to reduce your home's electricity consumption.

City 800

Carlos Calado

Excellence

The speed of delivery and the quality of the equipment and support.

shahed

Excellent Solar Investment and Outstanding Service

Purchasing the solar system has been a great decision. We’ve reduced our electricity bills by over 50% with just four solar panels. The service was very fast, and the advice was equally excellent—they helped us throughout the entire documentation process. We’ll continue buying their products because we find them to be high quality, and their customer service is outstanding

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