Expanding Your Home Battery: Adding More Capacity

Why would you expand your home battery?

You purchased a home battery and are pleased with the savings. But your consumption is growing: perhaps you've bought an electric car, had a heat pump installed, or your family has grown. The surplus solar power you produce during the day no longer fits in your current battery.

In that situation, you don't need to replace your entire system. Many home battery brands offer modular expansion: you simply add extra battery modules to your existing system. Faster, cheaper, and less wasteful.

Modular vs non-modular

Not all home batteries are expandable. The difference lies in the system design:

Modular systems (expandable)

With a modular system, you can add extra battery modules to your existing setup. The inverter and BMS support multiple modules. This is by far the most popular and cost-effective approach. Examples: Anker SOLIX Solarbank 2 (up to 4 modules, max 9.6 kWh), Dyness Tower (stackable up to 20 kWh), Pylontech Force H3 (up to 6 modules, max 17.5 kWh).

Non-modular systems

Some systems are not expandable. They consist of a single fixed unit with a predetermined capacity. If you want more capacity, you need to add a second system in parallel or replace the existing system. This is more expensive and complex.

Expansion options by brand

Here's an overview of the expansion options for the brands that HES sells:

Most expansions are relatively straightforward: with plug & play systems you can do it yourself, while permanently wired systems require a short visit from an installer.

When does expanding make sense?

Expansion is worthwhile in these situations:

• Your battery is fully charged daily: surplus is still being lost to the grid
• You've purchased an EV: the extra 2,000-4,000 kWh/year demands more storage capacity
• You've added more solar panels: more production = more surplus = more storage needed
• You've switched to a dynamic contract: more capacity = more price arbitrage = more savings
• Backup power needs: you want to be independent for longer during power outages

Cost of expansion

Expanding is generally cheaper per kWh than the initial purchase, because you reuse the existing inverter, wiring, and installation. You only pay for the extra battery module(s).

An extra module for the Anker SOLIX Solarbank 2 costs approximately €499-€699 (1.6 kWh per module). For the Dyness Tower, an extra module is around €1,500-€2,000 (5.12 kWh). The cost per kWh when expanding is typically 20-30% lower than the initial purchase.

Tips for a smooth expansion

Keep the following in mind when expanding your system:

• Check the firmware: ensure your existing system is running the latest firmware before expanding
• Matching battery version: with some brands, the modules must be from the same product generation
• Inverter capacity: check whether your inverter can handle the additional capacity
• Contact HES: we check compatibility and advise the best expansion option

Conclusion

Expanding your home battery is a smart and cost-effective way to increase your storage capacity. With modular systems from brands like Anker SOLIX, Dyness, and Pylontech, you can easily add extra capacity — without replacing your entire system.

Considering an expansion? Request advice and we'll check the options for your system, or browse our expansion modules in the shop.