Once you have solar panels, the next big decision is how to store all that energy. Most people default to lithium-ion batteries without knowing there's a safer alternative. What are saltwater batteries and how do they work – find out in this article.
Key takeaways
Saltwater batteries are exactly what they sound like – instead of using rare metals like lithium, they use sodium and regular water to store electricity. This makes them much simpler and safer than the batteries in your phone or electric car. The technical name is Aqueous Hybrid Ion technology, but that just means water-based battery system.
Every battery has three main parts: a positive side (cathode), a negative side (anode), and the liquid in between (electrolyte). When you charge the saltwater battery, tiny particles called sodium ions swim through the salt water from one side to the other. When you use the stored power, they swim back.
Sodium is everywhere – it's the sixth most common element on Earth. This means we'll never run out, unlike lithium which is harder to find and requires damaging mining operations.
Saltwater batteries have some great benefits that make them appealing for many homeowners. Here are the main reasons people choose them.
✓ Won't catch fire or explode: This is huge for home safety. Regular batteries use toxic chemicals that can overheat and cause fires. Saltwater batteries stay cool and calm even if something goes wrong. If a saltwater battery breaks, you get just salt water on the floor. You could literally drink what comes out, though we don't recommend it.
✓ Completely recyclable: When your saltwater battery reaches the end of its life in 10-15 years, every single part can be recycled safely. No toxic waste dumps, no environmental damage.
✓ Last longer with almost no maintenance: Most saltwater batteries work well for 3,000 to 5,000 charge cycles. That's 10-15 years of reliable service. Once installed, you basically forget about them until it's time to replace them.
✓ Use 100% of the stored power: With most lithium-ion batteries, you can only safely use 80-90% of the stored energy to keep the battery healthy. Saltwater batteries let you use every bit of stored power without damage.
Saltwater batteries aren't perfect for every home. Some of these problems might be deal-breakers, while others might not bother you much.
✗ Take up more space: Saltwater batteries need about twice as much room as lithium-ion batteries that store the same amount of power. If you have a small garage or limited space, this could be a problem.
✗ Cost more upfront: Expect to pay 20-30% more than comparable lithium-ion systems. But since they last longer and need no maintenance, the total cost over 15 years might be similar or even less.
✗ Aren't many manufacturers yet: The technology is still growing, so you have fewer choices and might wait longer to get your system installed. Finding qualified installers can also be harder.
✗ Charge more slowly: Saltwater batteries charge at about half the speed of lithium-ion batteries. On cloudy days or during high energy use periods, this slower charging might be noticeable.
Saltwater batteries work great in some situations but aren't the best choice for everyone. Here're the situations where these batteries would be your best bet.
Choosing between saltwater and lithium-ion batteries comes down to what matters most to you. Both technologies work well, but they're good for different situations and priorities.
Choose saltwater if safety matters most to you. If you have enough space, care about sustainability, and want a set-it-and-forget-it system for 15 years, saltwater batteries are worth the extra upfront cost.
Stick with lithium-ion if space is tight or budget is your main concern. Homes with limited installation areas, tight budgets, or needs for maximum power in minimum space should probably go with proven lithium-ion technology.
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Years of experience in translation and a love of nature help Julia find the right words to encourage going solar. She joined the team in 2023 and is happy to make her contribution to a greener future.
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