How to Build a High Voltage Energy Storage System with Sodium ion Battery​ in Germany

On May 19, 2024, a Client from Germany reached out to Seplos, informing the team that he needed to build an energy storage system of approximately 70kWh to store the energy generated by his 24.9kWp photovoltaic panels. His goal was to cope with Europe’s rising electricity costs and increasingly unstable energy supply. He expressed interest in using sodium-ion batteries as the storage medium to construct a high-voltage system—an approach rarely seen, even globally. The Seplos team thoroughly assessed the technical feasibility of the project and ultimately confirmed a 70kWh high-voltage sodium-ion system solution.

The project was successfully commissioned in March 2025 and is currently operating smoothly, allowing the Client to achieve true energy independence.

“It brings me freedom,” the German Client said.

Part 1: Why Consider Sodium-ion Batteries for a High Voltage System?

To date, lithium iron phosphate (LiFePO4) batteries still dominate the energy storage field. However, in some performance aspects, they are not ideal. In contrast, sodium-ion batteries offer several advantages that LiFePO4 cannot match:

• Excellent thermal stability
• Wide operating temperature range
• Strong low-temperature performance—especially suited for Europe’s climate

Among these advantages, the Client chose sodium-ion batteries primarily for their thermal stability. When used in a high-voltage system, they significantly reduce the risk of thermal runaway, ensuring system safety.

“The sodium-ion battery decreases the chance of fire and virtually eliminates the thermal runaway effect,” said the Client.

And why a high-voltage system? The Client believed the most important reason is that high-voltage architecture provides optimal power conversion efficiency when transforming DC to AC (230V), minimizing energy loss.

Taking all factors into consideration, sodium-ion batteries proved to be the ideal choice for building a high-voltage system.

Part 2: How to Build a High Voltage Sodium-ion Battery Storage Project

Step 1: Determine electricity demand.

The Client owns a 24.9kWp solar array made up of 59 solar panels—enough to meet the household’s energy needs.

Step 2: Choose a suitable installation site for the high-voltage battery.

It is recommended to use a concrete-poured surface to support the storage cabinet. Seplos battery cabinets feature IP65 protection and can be installed outdoors.

Step 3: Pre-plan the cable routing.

Ensure cables are laid in waterproof, corrosion-resistant conduits and route connections between the PV side and load side properly.

Step 4: Install the battery cabinet, inverter, main control box, and battery modules, and connect all wiring.

A safe and reliable high-voltage storage system is now ready to go.

The Seplos high-voltage sodium-ion battery system offers a high degree of integration and plug-and-play functionality, making the entire setup process very simple and user-friendly.

Part 3: What Benefits Has the System Brought?

The system can fully meet household energy demands, reduce grid reliance (especially during peak hours), and enhance energy resilience during outages.

After running for nearly three months, the Client has already seen substantial benefits:

“I charge my EV daily, knowing it is from my PV energy. With automation, we achieved arbitrage capabilities that charge the battery in winter times for the lowest electricity charge and sell for the highest demand on the grid. This makes it economically viable, as well as supporting the changing grid infrastructure here in Germany,” he said.

The system not only provides stable home energy but also has potential for peak-shaving and valley-filling in a business environment.

Part 4: Is a Sodium-ion High Voltage System Suitable for Other European Users?

Based on the Client's experience, this storage project is absolutely suitable for users in Germany and across Europe, due to the following reasons:

• Matches the evolving grid infrastructure in Germany
• Enables true energy independence
• Performs well in low temperatures—ideal for European climates
• Highly stable and safe
• High energy conversion efficiency
• Highly integrated and easy to install

If you live in an area with unstable power supply and frequent outages—and most importantly, if you're looking to reduce your electricity costs—then a reliable, safe sodium-ion high-voltage system is a smart investment.