Expanding a home battery: which module fits and up to how many kWh?
Last updated: 17 October 2026 · By Team Multi-Solar, home batteries since 2022, Rotterdam
Expanding a home battery is only possible if the model is designed for it. You stack an expansion module of the same brand and the same series under the base unit, or you place a second complete battery next to the first. The maximum differs per model: from 12.72 kWh for the Marstek Venus A to 42 kWh for the Anker SOLIX Solarbank Max AC, and more for fixed systems. In the Netherlands, after expanding you update your registration on energieleveren.nl. Below you can see per model which expansion fits and up to how many kWh (reference date 17 October 2026).
Can you expand any home battery?
No. There are three situations:
- Modular. The battery consists of a base unit plus modules of the same series. You add a module later. Examples: Marstek Venus A and Venus D, Anker SOLIX Solarbank Max AC, Hoymiles HiBattery.
- With a second complete unit. The model has no separate modules, but you can have several units work together. Examples: Marstek Venus E 3.0, Growatt Aura 5000 and TSUN Solartrunk.
- Fixed capacity. Some models cannot be expanded. You then stay with the capacity you start with.
Do not combine brands. Each manufacturer uses its own battery management system (BMS) and its own communication. So you always expand a modular home battery with modules that the manufacturer specifies for that model.
Expansion module or second battery: what is the difference?
| Expansion module | Second complete battery | |
|---|---|---|
| Inverter | one, in the base unit | each unit has its own inverter |
| App and meter | one app, one meter | together in the app, usually with one meter |
| Capacity (kWh) | grows | grows |
| Power (kW) | usually does not grow | grows along |
| Connection | same wall socket or circuit | a dedicated circuit per unit; with Marstek, inspection by an electrician |
| Examples | Venus A, Venus D, Anker BP7000, Hoymiles 4020 S | Venus E 3.0, Venus E 4.0 and Venus Max via SmartBox, Growatt Aura, TSUN |
So a home battery expansion module mainly means more storage. A second battery gives more storage and more power, but requires more work in the electrical panel.
Up to how many kWh can you expand? All models side by side
This is the maximum capacity per home battery according to the manufacturer. We checked all the models below in the datasheet, manual or on the manufacturer's website.
Plug-in batteries (plug & play)
| Model | Base | Expansion | Maximum | Power after expanding |
|---|---|---|---|---|
| Marstek Venus E 3.0 | 5.12 kWh | extra Venus E 3.0 unit | 46.08 kWh (9 units, three-phase via SmartBox) | 2.5 kW per unit, three-phase up to 22.5 kW |
| Marstek Venus E 4.0 | 5.024 kWh | extra unit via SmartBox | 15 kWh (3 units) | 3 kW per unit, 9 kW combined |
| Marstek Venus Max | 10.048 kWh | extra unit via SmartBox | 30 kWh (3 units) | 3.6 kW per unit, 10.8 kW combined |
| Marstek Venus A | 2.12 kWh | Venus A module, 2.12 kWh | 12.72 kWh (base + 5) | 1.2 kW, does not grow along |
| Marstek Venus D | 2.56 kWh | Venus D module, 2.56 kWh | 15.36 kWh (6 modules) | 2.2 kW, does not grow along |
| HYXi HALO | 3.014 kWh | HALO module, 3.014 kWh | 18.09 kWh (base + 5) | 800 W standard |
| Zendure SolarFlow 2400 AC+ and 2400 Pro | 2.4 kWh | AB1000, AB2000 or AB3000L | 16.8 kWh (max. 5 batteries) | 2.4 kW |
| Anker SOLIX Solarbank Max AC | 7 kWh | BP7000, 7 kWh | 42 kWh (base + 5) | 3.5 kW on a dedicated circuit |
| Anker SOLIX Solarbank 4 E5000 Pro | 5.024 kWh | BP5000 (according to manufacturer) | 30 kWh (base + 5) | 2.5 kW on a dedicated circuit |
| Sigenergy SigenMate 2700 Ultra | 2.688 kWh | SigenMate BAT 2700, 2.688 kWh | 18.8 kWh per system (base + 6) | – |
| Hoymiles HiBattery 4020 AC | 4.02 kWh | HiBattery 4020 S, 4.02 kWh | 16.08 kWh (base + 3) | discharge 2,000 W, with modules 2,500 W |
| Growatt Aura 5000 | 5.024 kWh | extra Aura unit with parallel cable | approx. 20 kWh (max. 4 units recommended) | per unit |
| TSUN Solartrunk | 5.12 kWh | extra unit | approx. 20.5 kWh (max. 4 units) | 2.5 kW per unit |
Fixed systems (installation via quote)
| Model | Base | Expansion | Maximum |
|---|---|---|---|
| Marstek Venus X | 10 kWh | extra battery (according to manufacturer) | 60 kWh (base + 5) |
| Hoymiles HiOne | 8 kWh | HiOne-8B-G3, 8 kWh | 32 kWh per tower, 64 kWh per inverter (2 towers) |
| Growatt APX 2.0 | 5 kWh | APX 5.0P-B3, 5 kWh | 30 kWh (master + 5) |
| AlphaESS Smile G3 | 3.8 or 9.3 kWh | BAT 3.8S or BAT 9.3S | 9.3S: 4 modules on single-phase (37.2 kWh); 3.8S: max. 6 (23.0 kWh) |
| Huawei LUNA2000-S1 | 6.9 kWh | LUNA2000-7-E1, 6.9 kWh | 20.7 kWh per power module (3 modules) |
| Tesla Powerwall 3 | 13.5 kWh | Expansion Pack, 13.5 kWh | 54 kWh per Powerwall 3 (base + 3) |
Reference date 17 October 2026. Maximums according to the manufacturer; a dash means the manufacturer does not specify it. You can find all modules among the expansion modules.
Does the power grow along when you expand?
Not always. Capacity (kWh) is how much you store; power (kW) is how much the battery delivers at the same time. An extra module mainly increases the capacity.
- Does not grow along: the Venus D stays at 2.2 kW, with 1 or with 6 modules. The Venus A stays at 1.2 kW.
- Grows a little: the Hoymiles HiBattery 4020 AC discharges 2,000 W without modules and 2,500 W with 1 to 3 modules (manual).
- Grows along with a second unit: the Venus E 4.0 goes up to 9 kW via the SmartBox, the Venus Max up to 10.8 kW.
With a plug-in battery, the wall socket remains the limit: via a standard wall socket you deliver a maximum of 800 W, however large the battery is. Read more in the 800 watt rule. How much capacity you really need is explained in how many kWh you need.
Can you combine old and new modules?
That is up to the manufacturer. An older module has less remaining capacity than a new one; read more about this in lifespan and remaining capacity. This is what the manufacturers say:
- Explicitly allowed: Growatt APX 2.0 allows old and new modules together, even with a different state of charge (Growatt). With Sigenergy SigenMate, new and old BATs are interchangeable (manual).
- Different types together: with the Zendure SolarFlow 2400 AC+, AB1000, AB2000 and AB3000L may be combined. With the Anker SOLIX Solarbank 3, BP1600 and BP2700 may be combined.
- Not allowed: Huawei LUNA2000-S1 modules do not fit on an S0 power module.
- Unknown: for Marstek we have not found a statement from the manufacturer about mixing generations.
If you want to expand a home battery later, choose a model now for which the manufacturer clearly regulates this.
Multiple plug-in batteries: when do you need an electrician?
Linking multiple home batteries is possible with a number of models, but not just like that. In the installation manual for the new P1 smart meter dongle (June 2026), Marstek prescribes:
- Multiple Venus E units together are possible from firmware V147, with CT003 firmware V116.
- All batteries use one P1 smart meter dongle. For each battery you set which phase it is on.
- A HomeWizard P1 meter or Shelly Pro 3EM can only be used with one battery. With multiple batteries you need a CT002 or CT003.
- If you place multiple batteries across the phases, or several on the same phase, inspection and approval by a certified electrician is mandatory.
According to the brochure, the Venus E 3.0 in a three-phase setup goes up to 46.08 kWh via the SmartBox. How many units you place per circuit follows local regulations (manual). So a second battery is not "simply plugged into another socket". A dedicated circuit or a three-phase setup means work in the electrical panel; installation is arranged via a quote.
You can read more about phases in single-phase or three-phase. Which meter suits your setup is explained in P1 meter or CT clamp. The difference between the Venus E 3.0 and 4.0 is explained in differences between the Venus E 3.0 and 4.0.
Do you need to register again at energieleveren.nl after expanding?
In the Netherlands you do not need to register again, but you do update your existing registration. Storage from 0.8 kW is registered via energieleveren.nl (the Dutch grid operators' registration portal), and you can change an existing registration (Netbeheer Nederland).
- Module added: update the capacity (kWh) in your existing registration.
- Second battery or inverter added, or a plug-in battery moved to a dedicated circuit: also report the new power (kW).
- Who does it: you do it yourself or have the installer do it. The obligation lies with you.
You can read more about registration in the 800 watt rule. Always check the current rules on energieleveren.nl.
Do extra rules apply to a very large home battery?
The Dutch guideline PGS 37-1 (version 1.1, April 2026) formally does not apply to private home batteries. However, it is recommended to apply the measures from that guideline above 20 kWh. Many systems in the table can exceed 20 kWh, such as the Venus E 3.0, the Anker SOLIX Solarbank Max AC, the Hoymiles HiOne and the Tesla Powerwall 3. Discuss the placement of a large system with your installer. You can read more about this in safety and PGS 37-1.
Buy big straight away or expand later?
Both are possible. Pay attention to four things when choosing:
- Choose a model whose maximum covers your expected consumption.
- Check whether the power grows along, or only the capacity.
- Check whether the manufacturer allows mixing old and new modules.
- If you have a dynamic contract, power often counts more heavily than kWh; read more about the dynamic energy contract.
If you are in doubt between a plug-in battery and a fixed system, first read plug-in or fixed.
Situation: which route suits you?
You want to start small with a plug-in battery. Choose a modular model, such as the Venus A, Venus D, Anker Solarbank, Hoymiles HiBattery or SigenMate. Take a look at the plug & play batteries and the expansion modules.
You already have a Venus E and want more power. Then you add a second unit, possibly with the SmartBox. This requires inspection by an electrician; request a quote. You can find all Marstek models under Marstek.
You have high consumption, three-phase or want more than 20 kWh. Choose a fixed battery. Take a look at the fixed home batteries; installation is arranged via a quote.
Frequently asked questions
Can you combine two brands of home battery?
No. Each manufacturer uses its own battery management system and its own communication. Expand with modules or units that the manufacturer specifies for your model.
Do you need an electrician to expand a plug-in battery?
You place a module under a plug-in battery according to the manual, with the system switched off. If, with Marstek, you place multiple batteries across the phases or on one phase, inspection and approval by a certified electrician is mandatory.
Can I install an expansion module myself?
With plug-in models you stack the module according to the manual, with the system switched off. With fixed systems the installer does this.
Does the warranty lapse if you add a module later?
Not if you use a module that the manufacturer specifies for that model and follow the manual. With Sigenergy SigenMate, the warranty lapses if you expand while the system is switched on (manual).
Do I see the extra capacity in the app straight away?
With Anker, Zendure and the Venus D, among others, a new module is recognised automatically according to the product data. After installing, check in the app whether the number of modules and the total capacity are correct.
Should you buy big straight away or can you expand later?
Expanding later is possible if the model is modular. In that case, choose a model whose maximum matches what you expect to need later.
Not sure which module fits your battery? View the expansion modules or request a quote for a larger system.
Sources
- Marstek, brochure Venus E 3.0 (2026), user manual Venus E 3.0 (8 May 2025), brochures Venus E 4.0, Venus E Max, Venus D and Venus X
- Marstek Netherlands, installation manual new P1 meter (June 2026)
- Marstek, press release SmartBox (31 May 2026); marstek.de, Venus A expansion battery (consulted 17 October 2026)
- HYXi, datasheet HYX-MS3000AC/HYX-MS3000B, version 1.5 (28 April 2026)
- Zendure, manuals SolarFlow 2400 AC+ (22 January 2026) and 2400 Pro (11 March 2026)
- Anker, datasheet Solarbank Max AC (26 May 2026); ankersolix.com, Solarbank 3 and Solarbank 4 Pro (consulted 17 October 2026)
- Hoymiles, datasheet and manual HiBattery 4020 AC; datasheet HiOne
- Sigenergy, manual and datasheet SigenMate
- Growatt, manual Aura 5000 (23 January 2026); growatt.com, APX HV Battery 2.0
- TSUN, datasheet Solartrunk (27 February 2026)
- AlphaESS, datasheets Smile G3 BAT 9.3S and BAT 3.8S; Huawei, LUNA2000-S1; Tesla, datasheet Powerwall 3
- Netbeheer Nederland, "Nieuwe elektriciteitsopslageenheid? Registreer deze dan!" (6 July 2022)
- PGS 37-1:2023, version 1.1 (April 2026)
- Product data multi-solar.nl (17 October 2026)