Gel Batteries vs Lithium-Ion: Which One Is Best for Solar?
If you looking to install a solar panel system either through a hybrid or off-grid approach, then you need some form of battery storage to keep your system running as intended. Like many products on the market, there are no loads of choices for consumers so it can be hard to decide where to start and what is the best product to ultimately choose for your system. In this post, we going to discuss in depth the differences between gel and lithium-ion batteries and most importantly what is the best one to choose for your solar energy system.
What’s the Difference Between Gel and Lithium-Ion Batteries?
Gel batteries are a type of sealed lead-acid battery. They use a thick, jelly-like substance that prevents leaks and doesn’t require maintenance. These are deep-cycle batteries, meaning they’re built to discharge slowly and recharge again and again. For many years, gel batteries were the go-to choice for when it came to installing solar systems, especially for off-grid systems that require adequate battery storage to function. Lithium-ion batteries, on the other hand, make use of lithium cell chemistry or otherwise more commonly known as lithium iron phosphate (LiFePO4) which is the name you would likely see on products. This helps them to deliver far higher energy density, faster charging, and a longer lifespan. Lithium-ion batteries have quickly become the preferred option for solar company when installing systems.
Performance: Lithium Batteries have a higher (RTE)
One of the major reasons why consumers and solar companies are choosing to utilise lithium-ion batteries is due to their performance benefits. There is something called the round-trip efficiency (RTE) which measures how efficiently a battery can store and discharge energy or otherwise the ratio between useful energy input and output. When it comes to lithium-ion batteries you can expect anywhere between 85-95% round trip efficiency with a good quality battery from a reputable supplier. To put this into context, this means that for every 100W of solar energy you generate around 90% makes it back to your appliances which ultimately means more electricity to power your home or business and less wastage. Whereas, with gel batteries that this figure drops to around 70% which means that more of the power you generate through your solar system is being wasted due to the batteries efficiency. Lithium batteries allow you to store more of your generated energy, access more of it on demand, and do so without massive losses or voltage drops. In simple terms: lithium delivers stronger, more consistent power - which is exactly what you want in a solar setup.
Lifespan and Durability: Lithium Wins Again
Another major advantage of lithium-ion batteries is their cycle life which refers to the number of charge and discharge cycles a rechargeable battery can go through before the capacity of the battery is degraded. A single cycle is one full discharge and recharge and with lithium-ion batteries you can expect a much higher cycle life compared to gel batteries.
Here’s a rough idea of what to expect:
• Gel batteries: Around 1,500–2,000 cycles
• Lithium-ion (LiFePO4): 4,000 to 5000+ cycles
To put that into perspective, if you discharge your batteries once per day, which can be very common in larger off-grid solar systems setups, gel batteries might last between 4-5 years. Whereas, with lithium-ion batteries you could be looking at 10-15 years of usage. Lithium batteries often do have a higher upfront cost, but this can work out more cost effective in the longer term as you don’t need to replace them nearly as often.
Charging Time: Lithium Is Much Faster
One of the major disadvantages of gel batteries is the length of time they take to charge, with an estimate of somewhere between 6-8 hours to fully charge a gel battery bank. When it comes to lithium-ion batteries these generally charger much quicker, with most batteries being able to go from 0-100% in just 2-3 hours, depending on your setup. This can give your home or business a major advantage especially if you live in an area with limited sunlight or during winter when the length of days is much shorter. Additionally, lithium batteries accept higher charge currents, which means they make better use of your solar panel output.
Space and Weight: Lithium Saves on Both
A 200Ah gel battery can weigh 60kg or more, and if your solar panel system requires more than one battery you could be dealing with a few hundred kilograms. When comparing this to a 200Ah 24V lithium-ion battery in South Africa this weighs somewhere around 28kg so less than half of that. One of the main advantages of lithium-ion batteries being smaller is that it can make them easier to transport and often less expensive as lots of courier’s charge based on dimensions and weight of the product and they can save you space in your cabinet or garage depending on where the battery is eventually installed.
Price: Gel Is Cheaper Upfront, But…
When it comes to this category, gel batteries have the upper hand as they are often cheaper compared to their lithium-ion counterparts. Your upfront cost for a gel battery will be less but over the longer term this may reduce due to lithium-ion batteries having a longer lifespan. In South Africa, for example, a 200Ah gel battery may cost around R3,000 to R4,500, while a lithium-ion equivalent may cost around R10,000 to R18,000, depending on the brand.
But here’s the thing: you get what you pay for.
• Gel batteries need to be replaced every 3–5 years.
• Lithium batteries can last 10+ years.
• Gel batteries can only be discharged to 50% without shortening their lifespan.
• Lithium batteries can regularly be discharged to 80–90%.
So, while the upfront cost of lithium is higher, it offers better long-term value, especially when you factor in replacements, downtime, and energy savings.
Safety and Maintenance
Both battery types are generally safe when installed correctly, but they behave differently. Gel batteries are stable, spill-proof, and sealed. Lithium batteries, especially modern LiFePO4 models, are also safe - but they rely heavily on Battery Management Systems (BMS) to monitor and balance cells. A good BMS will protect your lithium batteries from overheating, overcharging, and deep discharge. In practice, most lithium batteries for sale in South Africa come with built-in BMS features, especially the popular products and brands like the Deye SE-G5.3 lithium battery, BX51100 Dyness lithium battery or the Hina PowerGem wall mounted lithium battery. Maintenance-wise, both gel and lithium-ion batteries require little to no maintenance meaning you don’t have to stress about this.
What Should you Choose?
If you’re looking for a battery for your solar panel system that’s meant to last and you don’t want to replace it in roughly the next 5 years, then your go should be a lithium-ion battery. They have better performance features, last longer and are more compact. The initial investment is higher, but you won’t need to replace them every few years.
Looking for options? Start by searching for:
• 24V lithium-ion battery South Africa
• Lithium solar batteries for sale
• Best lithium-ion battery for solar
On the other hand, if you’re on a tight budget or need a basic short-term solution then a gel battery will be fit for purpose. They’re affordable, simple to use, and perfectly suitable for backup systems, lights, or low-demand solar projects. Just know that you’ll be replacing them sooner, and you’ll get less power overall from the same capacity.
Final Thoughts
Choosing the right solar battery backup can make a massive difference in terms of the overall efficiency of your system. While gel batteries still have their place in the market, there’s no denying that currently lithium-ion batteries are the future of solar battery storage solutions. If you’re seriously considering going off the grid and want to maximise your energy efficiency, then choosing lithium-ion batteries is the way to go.