Sodium-ion or lithium (LFP)? The comparison for home batteries

How a sodium-ion battery works

Sodium-ion batteries work on the same principle as lithium-ion batteries: during charging and discharging, ions move between two electrodes. Instead of lithium ions they are sodium ions. Sodium can be obtained from common salt, for example, and is abundant worldwide.

According to the International Energy Agency (IEA), sodium-ion batteries need neither lithium nor graphite. Depending on the cell chemistry, other metals are used. The Heiwit HEIWIT-NA-48V210Ah contains no lithium or cobalt; the new HEIWIT-NA-48V170Ah (from early 2027) uses polyanionic NFPP cells based on sodium, iron and phosphate.

Not to be confused with salt-water batteries (aqueous electrolyte) and high-temperature sodium-nickel-chloride batteries, often sold as "salt batteries": these are different technologies.

The comparison in figures

Energy density and cold behaviour according to the IEA (February 2026), market shares according to Swissolar's Batteriemonitor Schweiz 2026. Because of the lower energy density, a sodium-ion battery is a little larger and heavier for the same capacity. For a home battery in the basement this is rarely decisive; weight and space matter mainly in cars.

Cold: garage, basement, mountain areas

The IEA names low-temperature performance as one of the main advantages of sodium-ion technology. The Heiwit HEIWIT-NA-48V210Ah discharges from −25 °C to +60 °C and charges from 0 °C to +60 °C.

It is an indoor device (IP20): a dry room, even unheated, such as a basement or garage is possible; outdoor installation is not. Below 0 °C the battery delivers power but does not charge.

Safety

Sodium-ion chemistry is considered more thermally stable than many lithium chemistries. In Heiwit's abuse tests (mechanical damage, short circuit) the cells did not go into thermal runaway. According to Swissolar, LFP is also robust and more thermally stable than other lithium-ion systems.

No battery has zero risk. Safety depends on the whole system: cells, battery management system (BMS), inverter, location and professional installation. The Swiss fire-protection rules for home batteries are explained in the guide Home batteries in Switzerland.

Lifetime and warranty

In the laboratory endurance test the HEIWIT-NA-48V210Ah reached more than 6,500 cycles at 90% depth of discharge with over 70% remaining capacity. For the HEIWIT-NA-48V170Ah with NFPP cells, Heiwit expects 9,000 cycles at 95% depth of discharge based on the cell qualification tests. Both are test results, not guarantees.

Heiwit gives a 10-year warranty on the battery or a returned-energy amount, whichever is reached first. In Switzerland a battery is often not fully charged every day in winter because of low solar production, so the number of full cycles per year is usually below 365.

Price

According to the IEA (February 2026), lithium prices are not yet high enough for sodium-ion batteries to undercut LFP in most applications; in particularly cold climates they are already cost-effective for electric vehicles and stationary storage.

At SodiumStorage.ch one HEIWIT-NA-48V210Ah module with 10 kWh costs CHF 3’896.– incl. VAT, about CHF 390.– per kWh of nominal capacity or CHF 433.– per usable kWh. Inverter, accessories, shipping and installation come on top. For comparison: according to Swissolar, an installed 15 kWh home battery cost about CHF 8’850.– on average in Switzerland in 2025, everything included.

Who sodium-ion suits

• Batteries in cool rooms: unheated basement, garage, house in the mountains.
• Anyone who wants a system without lithium and cobalt.
• New PV systems or retrofits with a 48 V hybrid inverter (Heiwit VIRGO or LYBRA).
• Less suitable when space or floor load at the installation site is very limited.