The battery is a central part of any home backup, off-grid system, or portable power source. Especially one with solar. It absorbs, stores, and provides the energy you depend on.
That’s why finding the best off-grid solar battery is crucial. But understanding different battery types can be confusing. Knowing which battery is right for you can be even harder. We’re solar power experts here to lead the way.
After reading this, you’ll be able to understand lead-acid vs. lithium ion and be able to pick out the best lithium battery for your off-grid solar system or solar generator.
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Snapshot of Choosing the Right Battery
Here’s a quick summary of what you need to know to pick the right battery for your backup or off-grid system. For you to get the best energy storage for solar panels or other power sources.
Factors to Consider
Compare batteries by reviewing these factors:
- Capacity: How much energy it can store
- Life cycle: The number of times you can charge and discharge it
- Energy density: Higher density means smaller, lighter batteries
- Discharge ability: How close to zero you can discharge (and how fast)
- Efficiency: How much energy is lost between charge and discharge
- Cost: Based on the amount of usable energy and expected life
Lead-Acid vs. Lithium Ion
There are two categories of batteries used for off-grid energy: lead-acid and lithium-ion. Both have subtypes which we’ll cover in more detail.
Lithium Ion
- Modern tech found in most portable consumer electronics, usually using lithium iron phosphate
- Pros: Longer lifespan, can fully discharge, more compact
- Cons: Higher cost
- Subtypes: Nickel manganese cobalt (NMC), lithium iron phosphate (LiFePO4), and others
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Lead-Acid
- Older technology based on lead plates and sulfuric acid
- Pros: Affordable and well-tested
- Cons: Can’t fully discharge, shorter lifespan, lower density (heavier, bigger)
- Subtypes: Flooded acid, gelled acid, absorbed glass mat (AGM), and deep cycle
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WEIZE 12V 100AH Deep Cycle Gel Lead Acid Battery |
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Common Uses for Each Battery Type
Most portable consumer electronics feature lithium-ion batteries. This includes popular portable power stations, solar generators, and other off-grid energy systems.
Lithium provides compact size, long lifespan, and full discharge ability. They make the best energy storage for solar panels. Most companies use LiFePO4 technology. But you can find NMC and semi-solid state lithium batteries in power stations and solar generators.
The best solar generators with lithium batteries include EcoFlow Delta Pro Ultra, Bluetti AC500, and Anker Solix F3600. They all use the most advanced LiFePO4 lithium ion (LFP) batteries.
Lead-acid batteries are still widely used as car starter batteries. They’re also a popular option for DIY solar systems since they have a lower cost. But it comes at the expense of shorter life, larger size, and discharge limits.
| Best Overall | Best Mid-Level | Best Budget |
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EcoFlow DELTA Pro Ultra |
BLUETTI AC500 + B300S Home Battery Backup |
Anker Solix F3800 Portable Power Station |
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| Buy on Amazon | Buy on Amazon | Buy on Amazon |
Does Your Solar System Need a Battery?
Many solar experts do NOT recommend adding batteries to your home. This makes sense for some people who want the cheapest solar system. But that’s only if you are on the grid and do not want a reliable backup system. Without batteries, your solar system costs less.
If you want to create a home backup energy source or any off-grid electrical system, batteries are essential.
Batteries absorb and store energy from solar, fuel generators, grid outlets, or other power sources. Batteries allow you to use that power whenever you want. Even if the sun isn’t shining, the fuel generator isn’t running, or there’s a grid outage.
They serve as the heart of every off-grid energy system, including those for portable power stations and solar generators.
In-Depth: Battery Technology Insights
Now that you have a general idea of what we’re looking at, let’s dive deep into the details of the options for off-grid solar batteries.
Lead-Acid Batteries
Lead-acid batteries were invented in the 19th century as the first rechargeable battery. Modern improvements have come a long way. Yet the basics in lead-acid batteries remain the same. Lead plates are submerged in a sulfuric acid solution. When you add a charge, a chemical reaction allows the plates to absorb the energy to use later.
Some people use this battery type for off-grid systems because they are affordable. You may even be able to repurpose batteries from other systems to give them a second life. Another benefit is that they can handle a high rate of discharge (can send out big power very quickly).
Even if they’re not the best batteries for off-grid solar, they’ll still function as needed.
Why People Avoid Lead-Acid Solar Batteries
There are two reasons why people usually avoid lead-acid (if their budget allows):
- Depth of discharge: Even the “deep cycle” lead-acid batteries must keep ~50% of the battery’s capacity at all times.
- Limited life cycles: Can only be charged and discharged about 500 times before it starts to seriously degrade.
When you want a battery for an off-grid solar system, these problems with lead acid cause many people to look elsewhere. Since you can only use 50%, you need to double the amount of capacity compared to lithium. And you’ll have to replace them about every 500 cycles, which could be less than two years.
Taking these into consideration, the lead-acid affordability might not be as good of a deal as you thought. Then again, the upfront cost will be much lower.
Types of Lead-Acid Batteries
Within lead-acid, there are three main types:
- Flooded: Most basic and affordable type with a flooded wet cell that requires checking the fluid level.
- Gelled Electrolyte (GEL): An improved type that adds silica to the sulfuric acid solution. Sealed and maintenance-free. Good for mobile use.
- Advanced Glass Mat (AGM): The most advanced version where acid is held in place by a fine glass mat. Best lead acid for moving situations.
You can also find “deep cycle” lead-acid batteries, available as GEL and AGM. They use thicker plates to allow you to use more of the stored energy without damaging the battery. But they still aren’t to be discharged past 50%.
Can you make an AGM solar bank? Absolutely. And plenty of people do. Don’t let perfection get in the way of progress.
- Lead Acid: Widely used due to its reliability and cost-effectiveness.
- Pros: Affordable, robust, and well-understood technology.
- Cons: Heavy, lower energy density, and requires regular maintenance.
- Maintenance: Regular checking of electrolyte levels (unless sealed) and terminal cleaning.
- Best For: Stationary backup power, budget-friendly systems.
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WEIZE 12V 100AH Deep Cycle Gel Lead Acid Battery |
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WEIZE 12V 100Ah Deep Cycle Lead Acid Battery |
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Lithium Ion Batteries
Lithium-ion batteries are a much newer invention from the 1970s, recognized as one of the most impactful technologies ever created. And they’re in almost every portable consumer electronic device (phones, laptops, cameras) and many other electronic devices, including electric cars.
When it comes to the best off-grid solar batteries or the best battery for a home backup system, lithium steals the show. They last longer, can be almost fully discharged, and are more compact. The only downside is cost.
Lithium batteries work by sending lithium ions back and forth between a cathode and an anode. A charged battery stores the ions on the anode. When you connect devices and pull energy out of them, the ions move over to the cathode.
Why Off-Grid Lithium Batteries Are Good
They are lighter and smaller than lead acid. Much higher density. If space is tight or you don’t want to weigh down your RV, lithium hits the mark.
Where lead-acid batteries start to have issues after ~500 cycles or less, lithium-ion batteries can have 2,000 or more cycles (some are rated at 3,000). The best lithium batteries for solar, off-grid, or home backup systems will last about 10 years of constant use. Energy storage for solar panels that can last season after season, year after year.
On top of that, you can use almost all of the energy stored within a lithium battery. While lead-acid needs to keep about 50% of its capacity, you can run lithium down to when it says 0%.
Note: Keep a lithium battery between 20% to 80% to achieve the longest lifespan. And for long-term storage, it’s best to stay within this range. Finally, make sure to cycle from 0% to 100% now and then to reset the battery management system (BMS).
The Downsides of Lithium
It’s not all sunshine and butterflies, even with the perfect solar battery. There are two main downsides to lithium batteries:
- Cost: The price of this battery type is much higher. For big solar or backup systems, that can add up.
- Cold weather: Cold weather charging requires a heating element. The best lithium batteries have a built-in one.
If you can afford them, lithium will do much better and last about three times as long as lead acid. Just make sure to get one suitable for cold weather if the batteries will be used in sub-freezing temperatures.
The Many Types of Lithium
There are no less than six types of lithium-ion batteries. But when it comes down to solar batteries, there are only two major options.
By far the most common is lithium iron phosphate (LiFePO4 or LFP). This is the gold standard in modern battery technology, including solar system batteries. They last the longest, are the safest (less prone to thermal runaway), and are used by the best solar generator companies.
You’ll find LiFePO4 batteries inside of EcoFlow, Bluetti, and Anker systems. And plenty of DIY solar systems for off-grid or backup solutions use LiFePO4. Whether you’re building a battery from scratch with individual cells or buying an easy-to-use solar generator, the LiFePO4 battery will be excellent.
- LiFePO4 (Lithium Iron Phosphate or LFP)
- Description: Stands out for safety and longevity, with a stable chemistry that reduces risks of thermal runaway.
- Pros: Extremely safe, long cycle life, stable performance.
- Cons: Lower energy density than NMC, higher cost than lead acid.
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EcoFlow DELTA Pro Ultra |
DPU on EcoFlow DPU on Amazon |
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BLUETTI AC500 + B300S Home Battery Backup |
AC500 on Bluetti AC500 on Amazon |
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Anker Solix F3800 Portable Power Station |
F3800 on Anker F3800 on Amazon |
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Renogy 12V 200Ah Pro Smart Lithium Iron Phosphate Battery |
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Battle Born Batteries Lithium-Ion (LiFePO4) Deep Cycle 12V Battery 100Ah |
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Litime 12V 200Ah 2560Wh LiFePO4 Lithium Battery |
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The other common lithium battery type is nickel manganese cobalt oxide (NMC). This is another top choice in lithium technology that certain reputable brands use. Jackery is a top manufacturer that uses NMC batteries in many of its solar generators. They’re also used in many electric vehicles due to their higher density.
NMCs have slightly shorter lifespans and are less safe (require thermal management systems). LFP are also considered more eco-friendly because NMC relies on cobalt.
- NMC (Nickel Manganese Cobalt)
- Description: Known for a good balance between energy density and safety, common in electric vehicles.
- Pros: High energy density, good thermal stability.
- Cons: More expensive, requires cobalt.
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Jackery Explorer 2000 Plus Portable Power Station |
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Semi-Solid and Solid-State Batteries
The next generation of lithium battery technology is solid-state technology. By removing the liquid electrolyte solution, solid-state ones would have greater density and safety. At the moment, solid-state batteries are still slightly out of reach for practical consumer applications.
But semi-solid state batteries are being introduced. This is an advanced battery pushing toward solid-state, offering better performance and safety over the other types of lithium.
The BougeRV Rover 2000 portable power station has semi-solid state battery technology, pushing forward past competition.
- Semi-Solid State
- Description: A novel approach blending aspects of liquid electrolyte and solid-state technologies, aiming for safer and more durable batteries.
- Pros: Potentially safer, higher energy density than traditional lithium-ion.
- Cons: Recent development, long-term performance not tested.
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BougeRV ROVER2000 Semi-Solid State Portable Power Station |
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Which Battery Do You Need for Solar Energy Storage?
There’s no one-size-fits-all answer to finding which battery you need. Everyone must balance costs, safety, lifespan, and performance to come up with the right battery bank for their off-grid or home backup.
If your budget allows, the LiFePO4 lithium-ion battery type (LFP) is your best bet. It has the longest life, the safest design, and all-around amazing performance. Take care of an LFP battery and it will last you many, many years with incredible performance.
On the other hand, a sealed gel or AGM lead-acid battery can also do the trick. Yes, you’ll have to replace it more often and you’ll have to be concerned about not using more than 50% of the capacity. But it can save a lot of cash for startup costs.
If lead-acid is what your budget works with, go for it. Account for long-term considerations if you can. Lead-acid replacement is likely to happen every 3 years or so. Lithium every 7-10 years. And you’ll need to get about double the capacity of lead-acid to equal the same lithium because you can’t use about 50% of the lead-acid battery’s capacity.
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Renogy 12V 200Ah Pro Smart Lithium Iron Phosphate Battery |
Buy on Renogy |
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Battle Born Batteries Lithium-Ion (LiFePO4) Deep Cycle 12V Battery 100Ah |
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Litime 12V 200Ah 2560Wh LiFePO4 Lithium Battery |
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Mighty Max Battery 12V 100Ah SLA AGM Battery Internal Thread |
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WEIZE 12V 100AH Deep Cycle Gel Lead Acid Battery |
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WEIZE 12V 100Ah Deep Cycle Lead Acid Battery |
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Time to Get Your Battery Bank
That’s all you need to know about solar batteries. Lead-acid is the more affordable way to go, but you’ll pay for it in the long run. And you’ll have to be more careful about your usage. Stick with LiFePO4 when available, making sure to deal with cold-weather charging issues.
Ready to add a battery and solar power to your home right away? Forget a DIY system and buy one of the best solar generators for home backup to add instant solar power to your home.
