Off Grid Solar Batteries: What Type's Best?
Are you wanting to use solar power with an off grid system? If so, you're going to need off grid batteries, and they better be reliable.
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If you use a grid-tied or hybrid system, you might not need batteries to run your solar power. However, for off grid systems, batteries are indispensable. Without them, storing solar energy for nighttime or cloudy days becomes impossible.
So what happens if your batteries fail or deplete too quickly? In that case, your home or RV would be left in the dark during sunless periods.
Avoid such inconveniences by reading on to learn the pros and cons of different battery types to choose the best one for your needs!
Off Grid Solar Batteries Are Not Just for Camping Anymore
In the past, solar batteries were mainly used in remote campsites and mountaintop cabins. They continue to be essential for boondocking and dry camping. However, with the trend of grid defection, solar setups are increasingly being installed in towns and cities too.
People are choosing to live off grid even where grid power is available. They're opting for eco-friendly tiny homes entirely dependent on solar power. Others are using solar panels on rooftops as backup power in areas with unreliable grids, while some save big by using solar as the primary source and the grid as a backup.
Therefore, off grid batteries today need to be reliable, long-lasting, and efficient. However, not all batteries meet these criteria equally. Below we’ll discuss different types of off grid solar batteries so you can decide which one is best for you.
What Are the Best Batteries for Solar Off-Grid Use?
Lead acid batteries have long been a staple in off grid solar setups. They were the original batteries and were ubiquitous in the early days of solar energy.
However, technology has advanced. While lead acid batteries still work, they no longer represent the best option available for off grid solar systems. Though they come with the lowest upfront cost, their benefits are somewhat limited.
Each battery type has its strengths and weaknesses. We'll examine the top contenders for off grid solar batteries: lead acid, AGM, sealed gel, and lithium. But first, let's discuss what you should look for in a battery regardless of its type.
Key Factors to Consider:
- Depth of Discharge (DoD): Indicates how much energy you can use before the battery starts to degrade.
- Capacity: The electrical energy the battery can store, measured in kWh. Most off grid batteries have around 10 kWh capacity, while U.S. households use about 30 kWh per day.
- Power: The battery's output capability, measured in kW.
- Round Trip Efficiency: Shows the difference between the energy used to charge the battery and the available energy. A higher percentage indicates a more efficient battery.
Having covered these essentials, let’s dive into the pros and cons of each battery type. Here are the four most popular off grid solar batteries available today.
Lead Acid Batteries
Lead acid batteries have been around for over 150 years. They're popular for their low upfront cost.
Pros
- Low cost
- Good for short-term backup solar power
Cons
- Short lifespan (3-5 years)
- Require maintenance (watering, cleaning)
- Contain environmental toxins
- Not leak-proof; require ventilation
- Not ideal for infrequent visits to remote sites due to maintenance needs
- Usable capacity is 50%
Sealed Gel Cell Batteries
Sealed gel cell batteries have electrolytes stored in gel form, preventing spills. They are similar to AGM batteries.
Pros
- Can tolerate long periods without being charged
- Low self-discharge rate
- Longer cycle life than AGM batteries
- Maintenance-free
Cons
- Medium-high cost
- Not suitable for remote locations
- Charges slowly
- Short lifespan (2-5 years)
- Limited peak power delivery
- 50% usable capacity
AGM Off Grid Solar Batteries
AGM (Absorbed Glass Mat) batteries are similar to gel cell batteries and are sealed.
Pros
- Low maintenance
- Good for intermittent use, e.g., vacation cabins
- Better peak power delivery than gel batteries
- Spill-proof
- Low self-discharge rate
Cons
- Medium to high cost
- Not ideal for constant use in remote areas
- Susceptible to overcharging
- Short lifespan (4-6 years)
- 50% usable capacity
Lithium Off Grid Solar Batteries
LiFePO4 lithium batteries are the newest addition to off grid solar battery types and are currently the most reliable.
Pros
- Longest lifespan
- Protected from overcharging or undercharging
- Eco-friendly and leak-proof
- Maintenance-free
- Lowest lifetime cost
- Fastest charging type
- Suitable for long-term, short-term, and intermittent use
- Rarely needs replacement; ideal for remote locations
- Most energy-efficient
- 80-100% usable capacity
- Best for various climates
Cons
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Which Solar Batteries Should You Choose?
Energy needs vary for each person. Lead acid or gel type batteries may be sufficient for short-term testing of a solar setup.
However, considering efficiency, reliability, and lifetime cost, lithium batteries (e.g., our 12V 100Ah LiFePO4 battery) are the best choice among all off grid solar batteries. While the upfront cost is higher, lithium batteries ensure smooth, reliable power. Check out the latest options for lithium solar setups OMMO.
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Lithium-ion solar batteries are the most popular option for home energy storage because they last long, require little maintenance, and don’t take up as much space as other battery types. Lithium solar batteries typically cost between $12,000 and $20,000 to install.
When paired with solar panels, excess solar energy can be stored in the battery and used later, like at night or during a power outage. Depending on the area, lithium ion batteries can even help save extra money on electricity bills.
Let’s take a closer look at what you need to know about lithium-ion batteries before getting one installed.
How do lithium-ion batteries work as home storage?
Lithium batteries are rechargeable energy storage solutions that can be installed alone or paired with a solar energy system to store excess power.
Standalone lithium-ion batteries can be charged directly from the grid to provide homeowners with backup power in case of a power outage. They can also be used to avoid paying for peak electricity rates, by charging with grid power when electricity is cheap and discharging when it’s expensive.
Pairing a battery with solar will give you the most bang for your buck, especially if you don’t have access to net metering. The lithium battery can recharge with excess solar energy generated by your panels, so you can run your home entirely with solar even when the sun isn’t shining.
How much do lithium-ion solar batteries cost?
Lithium-ion solar batteries don’t come cheap, with installations ranging from $10,000 for a simple single-battery solution, to well over $30,000 for whole-home backup. This is significantly higher than that of installing lead-acid batteries, which typically run between $5,000 and $15,000.
Despite the price difference, people still tend to choose lithium-ion batteries over lead-acid because of increased performance and fewer maintenance concerns. The total cost of a solar battery installation depends on the battery brand you choose, the features it has, how many batteries you need, and labor costs.
Battery incentives can help lower costs. There are a number of solar battery incentives that help lower installation costs. The biggest is the federal tax credit, which is equal to 30% of the total costs of qualifying battery installations. There are a number of local battery incentives and rebates, pilot programs like Green Mountain Power's battery lease, and things like virtual power plant programs are becoming more popular, as well.
How much can you save annually with solar-plus-battery-storage?
What are the pros and cons of lithium-ion solar batteries?
Pros
Cons
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High cost
-
Thermal runaway
Advantages of lithium-ion solar batteries
Lithium-ion batteries are the most popular option for homeowners looking for battery storage for good reason. Here are some of the benefits of lithium-ion home batteries:
Higher depth of discharge (DoD)
The DoD of a battery is the amount of stored energy in the battery that has been used compared to the total capacity of the battery. Most batteries come with a recommended DoD to maintain their health.
Lithium-ion solar batteries are deep cycle batteries, so they have DoDs around 95%. Compare this to lithium ion batteries, which have DoDs closer to 50%. Basically, this means you can use more of the energy stored in a lithium-ion battery and you don’t have to charge it as often.
Long lifespan
Because lithium ion batteries have a high DoD and don’t need to be charged and recharged as often, they have a long lifespan.
Most lithium-ion solar batteries have a minimum warrantied lifespan of around 10 years, or a cycle life of 10,000 cycles - whichever comes first. Lead acid batteries, on the other hand, only have warrantied lifespans of around 5 years.
Higher energy density
The energy density of a battery is how much power the battery can hold relative to its physical size.
Lithium-ion batteries can store more power without taking up as much space as lead-acid batteries, which is great for homes where space is limited.
High efficiency
Lithium-ion batteries have a higher round-trip efficiency rating than other types of solar batteries on the market.
Efficiency refers to the amount of usable energy you get out of your battery compared to how much energy it took to store it. Lithium-ion batteries have efficiencies between 90 and 95%.
Less maintenance
Not having to worry about regular maintenance is one of those advantages that you can’t put a price on. Lithium-ion batteries require little to no regular maintenance - just make sure they're clear of debris. Some lead-acid batteries, on the other hand, require frequent off-gassing.
Disadvantages of lithium-ion solar batteries
Although lithium-ion batteries have numerous benefits, there are still some drawbacks.
High cost
Lithium-ion batteries tend to be the most expensive battery storage option, especially when compared to lead-acid batteries.
The good news is that solar battery systems qualify for incentives like the federal tax credit, which helps make lithium-ion batteries more affordable.
It’s also important to remember that while lead-acid batteries may be cheaper upfront, they have to be replaced more often, increasing your overall storage costs.
Thermal runaway
Lithium-ion batteries run a higher risk of thermal runaway, AKA overheating and catching on fire. While the risk is technically there, the chances of this happening with a properly installed lithium-ion battery are slim to none.
Popular lithium-ion solar battery brands
There are many lithium-ion solar batteries on the market. Some of the best solar battery brands include Enphase, Panasonic, and Tesla.
The following table outlines some other popular lithium-ion solar batteries on the market:
At $682 per kWh of storage, the Tesla Powerwall costs much less than most lithium-ion battery options. But, one of the other batteries on the market may better fit your needs.
Types of lithium-ion batteries
There are two main types of lithium-ion batteries used for home storage: nickel manganese cobalt (NMC) and lithium iron phosphate (LFP).
An NMC battery is a type of lithium-ion battery that has a cathode made of a combination of nickel, manganese, and cobalt. When people say "lithium-ion batteries," they're often referring to NMC batteries. These batteries are what created the mainstream popularity of lithium-ion due to their superior performance compared to lead-acid batteries. The Generac PWRcell, LG RESU Prime, and Tesla Powerwall 2 are NMC batteries.
LFP battery cathodes are made of lithium iron phosphate (LiFePO4) and are still considered lithium-ion batteries. The iron and phosphate used in the cathode are more abundant and less expensive than some of the materials used in NMC batteries, mainly cobalt. The Enphase IQ, Panasonic EverVolt, and Powerwall 3 use LFP technology.
More battery manufacturers have been switching to LFP batteries because they don’t contain expensive, toxic cobalt. LFP batteries are easier to recycle, a bit cheaper, longer lasting, and, most notably, safer. Aside from having fewer toxic metals, LFP batteries better handle temperature fluctuations and are even less likely to experience thermal runaway than their NMC counterparts.
How are lithium-ion batteries recycled?
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