Are sodium ion batteries the next big thing in solar storage?

Batteries are becoming a main staple of residential solar installations. You’ll need one if you want to store energy to use when the sun isn’t out, as well as during power outages. If you have an off-grid solar installation, your battery is literally the lifeline of your home.

At the moment, lithium ion (Li-ion) is the top choice for solar batteries, as this type is very reliable and can be found in leading battery storage products, including the Tesla Powerwall, Generac PWRcell, and LG Chem. 

However, sodium ion batteries are a promising technology, because they will be safer to use and theoretically cheaper to produce. That said, the technology has not moved much in the past few years, despite recent stories about breakthroughs.

Here’s a little energy storage joke:

• Q: Are sodium ion batteries coming soon?

• A: Na.

What is a sodium ion battery?

A sodium ion battery uses sodium as a charge carrier. The internal structure of sodium ion batteries is similar to lithium ion batteries, which is why they are often pitted against each other. Sodium ion batteries are rechargeable just like lithium ion, lead acid, and absorbent glass mat (AGM) batteries. 

Learn more:

• Are lithium ion solar batteries the best energy storage option?

• Should you choose a lead acid battery for solar storage?

• All about AGM batteries 

Development for sodium ion batteries dates back to the 1980’s and recently started picking up due to challenges with scaling lithium ion batteries, including rising material costs and the need to acquire large amounts of lithium to sustain battery production and demand. 

There has been extensive research associated with optimizing Na-ion battery cells, specifically related to using Prussian blue as a cathode material. The Na-ion battery pack is capable of taking on different usable shapes, ranging from traditional cylindrical batteries to rectangular pouches. These various form factors are ideal for commercialization, allowing this battery type to be used for energy storage, electric vehicles, and portable devices.

Sodium ion battery vs. lithium ion battery technologies

Let’s compare sodium ion batteries with two popular types of lithium ion batteries – nickel manganese cobalt (NMC) and lithium iron phosphate (LFP). 

These lithium ion batteries are the most common types of solar energy products used in residential solar photovoltaic (PV) systems.

	Sodium ion	NMC	LFP
Availability	Still under development	Widely available	Widely available
Cost	Cheapest	Cheaper	Most expensive
Energy density	Lowest	Highest	Moderate
Safety	Safest	Least safe	Safer than NMC
Round-trip efficiency	92%	90-95%	92-98%

Energy density and efficiency 

Sodium ion batteries have the lowest energy density out of the group, which means they take up more space than lithium ion batteries. NMC batteries have the highest energy density.

A 10 kilowatt-hour (kWh) lithium ion battery will take up less space inside your home than a 10 kWh sodium ion battery would, even though they have the same capacity. This could be an issue if you have limited space on your property, but because Na-ion batteries are still being developed, this could change in the future. 

All three battery technologies offer more than 90% round-trip efficiency. This means that the batteries are effective when it comes to minimizing energy losses, allowing more of the energy generated by your solar panels to be stored, instead of being lost during the storage process. 

Batteries with high round-trip efficiencies can consistently power appliances and devices for long periods of time. LFP batteries have a slightly higher round-trip efficiency than NMC and Na-ion batteries. However, the differences are very small and are only noticeable in large-scale solar installations.

Safety 

Solid-state sodium ion batteries are safer than Li-ion batteries because they are non-flammable and can operate effectively across a wide range of temperatures. Although stable, lithium batteries can be prone to catching on fire when improperly used, charged, or stored. 

Recently, the New York City Fire Department (FDNY) issued a warning about the fire risks of lithium ion batteries due to several incidents involving lithium ion batteries catching fire. However, these occurrences are rare and should not stop you from purchasing lithium ion batteries for solar energy storage at home. 

With that said, LFP is safer than NMC because it can withstand higher operating temperatures, while also handling more power. Compared to sodium ion batteries, lithium ion batteries have been tested extensively and have a reliable track record in the solar industry.

Cost 

Cost is a major factor in battery technology adoption; they add several thousands of dollars to a solar system installation. 

Sodium ion batteries are projected to have lower costs than lithium ion batteries because they use cheaper materials. Lithium ion batteries for solar energy storage typically cost between $7,000 and $14,000 before the federal solar tax credit, depending on the type and capacity. 

Lithium ion batteries heavily use lithium and cobalt in the manufacturing process. Cost for lithium is increasing, driven by inflation as well as high demand for electric vehicles and home energy storage. The sudden demand for the metal has led to a shortage and will likely persist in the coming years. Sodium ion batteries do not use any lithium, cobalt, or nickel.

In fact, the challenges associated with acquiring lithium are fueling the development of sodium ion batteries. Many believe a new type of battery should be released in order to keep up with demand for energy storage.

Availability 

There are some sodium ion batteries available for purchase, though most are under prototype or demo release. Online purchases for sodium ion batteries aren’t straightforward, requiring you to make a formal request to the manufacturing company. 

On the other hand, lithium ion batteries for solar energy storage systems are being sold by numerous battery manufacturers worldwide. These products are currently the battery technology of choice for both consumers and top brands or sellers. You can easily buy them online or from a local solar installer.

Companies developing sodium ion batteries

There are several companies on a quest to develop and launch sodium ion batteries. Many of these businesses have prototypes available and are coming close to delivering Na-ion batteries to mainstream consumers.

Bluetti 

Bluetti manufactures solar panels, as well as LFP batteries for portable use and home battery backup. 

Based in Nevada, the business announced a sodium ion solar generator in early 2022, but it is not yet available for sale. The product has a 3,000 watt-hour (Wh) capacity, and is expandable for high capacity requirements. Bluetti has a track record of success in the solar generator space, and if they can make a sodium battery appealing to the residential market, it could be a big deal. Keep an eye on this company for leading sodium ion solar battery solutions in the future.

Contemporary Amperex Technology (CATL) 

CATL is a global battery maker, and holds more than 30% market share for lithium ion batteries used in electric vehicles. 

Based in China, the company is in the process of developing its first-generation sodium ion battery line. It is focusing its efforts on increasing the energy density of the battery, which could help expand the applications of the product. 

CATL is a significant player in the nascent sodium ion battery space because it has the ability to quickly scale production due to its large operating capacity, which consists of more than 33,000 employees (as of 2020).

Natron Energy 

Natron Energy offers a compact sodium ion battery for very specific uses, including data centers, telecoms, and rack-mount applications. 

This product is compliant with Underwriters Laboratories (UL) safety standards, which is one of the challenges with bringing the battery to mainstream markets. The Na-ion battery boasts a long cycle life and is capable of delivering more power than lead acid batteries. 

Although available for purchase, the fast charge battery is insufficient for solar panel installations at home.

AMTE Power 

AMTE Power develops and manufactures batteries for commercial use. The company is in the process of launching a sodium ion battery for electrochemical energy storage and transportation in Q3 2022. It is working with Faradion, a sodium ion battery producer, to boost its manufacturing and sales efforts.

The company’s sodium ion battery is very slim, taking on the shape of a square pouch. The battery is low power and isn’t really suitable for home solar installation yet.

Sodium batteries: promising solution that’s still under development

Sodium ion batteries are next-generation solutions for the growing residential solar industry. 

Many view it as a way to scale energy storage, because, compared to lithium ion technology, it uses widely abundant and sustainable materials. Low production costs for sodium ion batteries could also boost product deployment. However, this battery type is still in the early stages of development and production. 

Sodium ion batteries, on paper, have plenty of advantages over existing lithium ion and lead acid batteries - particularly when it comes to sustainability. But these conventional batteries are tried and tested with a very long history and track record of reliable performance in real-world applications. In our view, this is what matters and what is heavily missing when it comes to sodium ion batteries. 

If sodium ion batteries prove to be a viable option for traditional solar batteries over the long term, then it would be easier to recommend them for home solar panel installations - but only time will tell. So how do you know when sodium ion batteries are reliable enough for solar panels? You would know the time is right to purchase them when:

• Local solar installation companies begin offering or recommending them

• You can easily buy the products online

Sodium ion batteries, so far, seem to be on the right track to serving as an alternative to traditional batteries in the future, but for now, there’s nothing wrong with committing to the currently-available lithium ion batteries for your solar installation.