Solar Batteries: Lithium Iron Phosphate vs Lead Acid

comparing lithium ion phosphate batteries to lead acid batteries

8 Reasons Lithium is Better for Solar Energy Storage

Sometimes newer isn’t better. But in the case of solar battery technology, the newer lithium iron phosphate batteries (LiFePO4, or LFP) defeat the older lead acid varieties in almost every way.

If you enjoy this article, you may also want to look into our comparison of popular solar power batteries and Tesla Powerwall alternatives.

Without getting too technical, here are 8 reasons lithium squashes lead if you’re looking to buy and install a solar energy system in your home or business:

1. Safe enough for Grandma to use

LFP solar batteries will not explode or catch fire. They use very stable chemical compounds. They are stable even at high temperatures. And if you’re wondering about those exploding laptops and cell phones from a few years ago, those were lithium-cobalt batteries. Not the same thing.

In contrast, lead batteries have all sorts of stuff that can go wrong without proper maintenance, like spilled or leaking acid. Which leads to reason #2.

2. No need for a “solar-sitter” while you’re on vacation

Your dog might need help while you’re gone, but your lithium iron solar battery will be just fine on its own. It needs no ongoing maintenance like voltage monitoring or refills.

In contrast, lead acid requires a lot of monitoring and upkeep. Otherwise, lots of things can go wrong, including leakage, loss of power, and a big hole in your wallet. Some varieties need more work than others, like refilling the electrolyte solution with fresh water and checking specific gravity. But all of them require more technical skill and attention. See this article for all the specialized work you have to do with lead acid solar batteries.

If you have lithium iron batteries, you avoid all that maintenance and risk.

3. This is a marathon, not a sprint. LFP lasts way longer.

Again, specific data varies by brand and type. But a typical lithium iron phosphate battery will last for 8-10 years and for thousands of cycles. The sonnenbatterie, a lithium iron phosphate solar storage battery used by Coastal Solar uses, is guaranteed for a minimum of 10 years and 10,000 cycles.

How much worse are lead acid batteries? They usually last less than 3 years, and the best ones might make it to 1000 cycles. So while lead batteries cost less up front, they won’t last nearly as long, and you’ll pay for multiple replacements before the LFP would have run out.

What’s a cycle? Think of your phone. When the battery light flashes, that means you’ve ‘discharged’ the battery. Once you ‘recharge’ it back to full power, that’s one cycle. How long a cycle lasts depends on a lot of factors, such as how far down you discharge it each time and the local temperature.

4. Solar batteries care about their weight too.

Lithium batteries generally weigh less than half of what comparable lead acid batteries weigh. This means lower shipping costs, less stress during installation, and less strain on your walls, or wherever you end up installing it.

lithium iron phosphate solar batteries beat lead acid batteries5. Lithium is “green,” even if you’re not.

You’ll have to discard your battery eventually. The chemicals in the LFP solar batteries are non-toxic and cause no harm to the environment. They contain no rare metals or what is commonly referred to as battery acid – which is very dangerous.

Lead batteries, on the other hand, use dangerous chemicals that are harmful – to you and to the fish. So even if you maintain it properly, disposing of a lead battery is environmentally problematic. Regardless of whether you consider yourself an ‘environmentalist,’ choosing lithium over lead is an easy way to help the planet and impress your friends.

6. Versatility, thy name is lithium iron phosphate

A stable battery is a huge advantage. It means you can orient it however is most convenient, and put it wherever you want. Lithium solar batteries like the sonnenbatterie can be installed indoors or outdoors, in any room of your house, and on the walls or on the floor.

While some lead acid batteries also offer some flexibility as far as not requiring it to sit a certain way, they do not offer the range of installation options of the LFPs.

7. Holding nothing back – full discharge

Remember the cycles? Lithium batteries can be fully discharged without risk and without loss of future capacity. That means longer cycles, and fewer of them.

Lead batteries can only be about 80% discharged, or they risk being damaged – this is another thing you have to monitor.

8. Stable in the face of boredom

Do batteries get bored when they aren’t being used? With LFP solar batteries, it doesn’t matter. Their capacity barely budges even when not in use, and they have minimal self-discharge. This is a huge advantage, because if you’re gone for a while or don’t need the battery for certain times of day, it will be at full capacity when you return.

But lead batteries do self-discharge and lose a lot more capacity even when not in continuous use. So you get less out of it when you need it.

There’s another battery issue called the “memory effect.” This problem actually doesn’t occur with either lithium iron phosphate or lead acid batteries, so in our little contest, they tie on this point. But it’s still good to know that the LFP holds its own on this issue.

What’s the memory effect? It’s when your battery seems to lose capacity over time at a faster rate than it should. Over time, all batteries wear out and don’t recharge as much, but this should happen at a slow rate. But some batteries have a peculiar habit of resetting their maximum based on how much you discharge it.

For example, some phones have this problem. If you only use half the capacity and then recharge it, the battery “remembers” a lower maximum capacity as a result. Thus, it stays charged for much less time in the future.

Lithium iron phosphate solar batteries do not suffer from the memory effect.

Have More Questions about Solar Batteries?

If you’re looking at your options for solar battery storage units, you can see now that LFPs are far superior to lead acid in almost every way. Want to keep learning on your own? See our complete guide to solar power batteries and energy storage systems.

If you have more questions about solar batteries, solar panel arrays, or whether it’s economically feasible for you to switch to solar for your business, farm or home, contact us today and a specialist will get in touch with you.


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