It is well known that lithium-ion batteries are the best way to store solar energy in small off-grid power systems.
Shop Solar Kits understands that off-grid solar systems are only as good as their ability to store power in the field. We've patched, tested and sold thousands of lithium-ion batteries over the years and are always working to find the best solar storage battery.
Here, we outline what to look for when buying a battery for solar system, then list 6 tips for selecting lithium battery for solar system.
Is lithium battery good for solar system?
These batteries work by using lithium ions to transfer energy between the cathode and anode. Lithium batteries are rechargeable batteries commonly used in off-grid and grid-tied solar energy systems for storing the energy generated by solar panels during the day and releasing it when it is needed, such as during periods of low sunlight or at night.
Here are the reasons that why lithium batteries are more widely used in solar system than lead-acid batteries.
Benefits of Lithium Battery for Solar System
Lithium batteries have several benefits for solar systems, including:
High energy density
Lithium batteries have a higher energy density than other battery types, meaning they can store more energy per unit of weight or volume. This makes them ideal for solar energy storage, where space and weight are often at a premium.
High cycle life
Lithium batteries have a longer cycle life than traditional lead-acid batteries. This means that they can be charged and discharged many more times without losing their capacity to hold a charge. This translates to a longer lifespan for the battery, which reduces the need for frequent replacement and ultimately lowers the overall cost of ownership.
Lithium batteries can be charged quickly, which is particularly useful in a solar energy system where the battery needs to be charged during peak sun hours. This ensures that the battery is fully charged before the sun sets, maximizing the amount of energy that can be stored.
Lithium batteries are virtually maintenance-free, unlike lead-acid batteries that require regular topping up with distilled water. This means that they can be left for long periods without attention, making them a convenient and hassle-free option for solar energy storage.
Lithium batteries have a higher charge and discharge efficiency compared to lead-acid batteries. This means more of the energy stored in the battery can be used, resulting in less waste and a more efficient system overall.
Overall, lithium batteries are a great choice for solar systems as they offer higher energy density, longer lifespan, faster charging, and better efficiency compared to other battery types.
Types of Lithium Battery for Solar
There are several types of lithium-ion batteries commonly used in solar energy storage systems:
Lithium Iron Phosphate (LiFePO4) Batteries
LiFePO4 are often considered the best option for solar systems due to their high energy density, long cycle life, and inherent safety features. They are also resistant to overheating and thermal runaway, making them ideal for use in harsh environments. However, they are typically more expensive than other types of lithium batteries.
Lithium Nickel Manganese Cobalt Oxide (NMC) Batteries
NMC batteries are known for their high energy density and long cycle life, making them a popular choice for solar systems. They are also relatively affordable compared to other types of lithium batteries. However, they can be prone to overheating and thermal runaway if not managed properly.
Lithium Titanate (LTO) Batteries
LTO batteries have a very long cycle life and can tolerate very high charge and discharge rates. They are also very safe and can operate at very low temperatures. However, they have a lower energy density compared to other lithium-ion batteries and are more expensive.
Lithium Nickel Cobalt Aluminum Oxide (NCA) batteries
NCA batteries are known for their high energy density, which allows for more energy storage in a smaller footprint. They also have a long cycle life and can withstand high discharge rates. However, they are more expensive than other types of lithium batteries and require careful management to prevent overheating and thermal runaway.
Lithium Manganese Oxide (LMO) batteries
LMO batteries are known for their high power density, which makes them ideal for applications that require a lot of power in a short amount of time. They also have a long cycle life and are relatively inexpensive compared to other types of lithium batteries. However, they have a lower energy density, which means they may not be the best option for solar systems that require a lot of energy storage.
Which Type of Lithium Battery is Best for Solar?
In terms of the best lithium-ion battery for a solar energy storage system, it depends on several factors such as budget, space available, energy requirements, and expected lifespan.
LiFePO4 batteries are a popular choice because they offer a good balance of cost, energy density, and cycle life. However, if space is limited and a higher energy density is required, NMC batteries might be a ideal choice. LTO batteries are ideal for applications that require very high charge and discharge rates or for extreme temperatures. Ultimately, it's important to evaluate the specific needs of the solar energy storage system before choosing the best battery type.
Ultimately, the best type of lithium battery for your solar system will depend on your specific requirements and budget. It is important to consider factors such as energy density, cycle life, power density, and safety features when making your decision. Additionally, you should work with a qualified installer or engineer to ensure that your solar system is designed to accommodate the specific type of battery you choose.
What to Look for When buying a Solar Battery
You can use lithium-ion batteries in golf carts, boats, and tons of other applications. While we focus on off-grid solar storage, there are six key features to consider about lithium-ion solar batteries before choosing the best battery for your application. So let's dive in.
Battery Capacity/How Long It Will Last
First and foremost, storage capacity is the most important thing to know about a 12v lithium-ion battery. Storage capacity is measured in watt-hours (Wh) or amp-hours (Ah) to approximate the battery discharge time.
Lithium-ion batteries come with the advantage of being able to discharge their capacity without damaging the system. As such, it is simple to calculate how long your battery will last.
Next, it is critical to verify a 12v lithium-ion battery’s estimated life cycle count before purchasing. Lithium solar batteries can be expensive, and life cycle counts help estimate the approximate lifespan of the storage.
Over time, batteries slowly degrade and lose a portion of their capacity to store electricity, known as the depth of discharge (DoD). Most commonly, lifecycles are an estimate of a number or range of full recharges before the battery reaches 80% DoD.
If a battery is rated at 1000Wh with 500 lifecycles at 80% DoD, then it can hold approximately 800Wh of electricity storage after 500 full uses.
All 12v lithium-ion batteries have an approximate shelf life which refers to the amount of time they can be left idle while maintaining their charge capacity. Sometimes, manufacturers refer to this as the maximum time between recharges, while others try to hide the term altogether.
A good shelf-life rating is critical if you plan to only use a 12v lithium-ion battery pack as an emergency source of power. In areas without sufficient sunlight, off-grid solar energy systems must have several 12v lithium-ion batteries on hand for extended periods of consumption.
If you use your lithium solar battery every day, then the shelf life isn’t nearly as important. In general, anything from 3 to 6 months is an average shelf life typical of high-quality lithium-ion batteries.
Of course, shelf life, lifecycles, and battery ratings mean nothing if your battery is defective. Like all electronics, lithium solar batteries may malfunction, so a good warranty is important to ensure the ongoing success of your off-grid system.
Long warranty periods, like seven, 10, and 12 years, can help you get the best return on investment for a lithium solar battery. Companies like Lion Energy provide lifetime warranties with some of their products. As always, it is important to read the fine print in a battery warranty and be careful not to do anything that would void a full refund.
Battery Management System (BMS) Features
Compared to AGM and lead-acid batteries, 12v lithium-ion batteries generally have more advanced battery management features. Advanced lithium-ion batteries with smart BMS temporarily absorb higher voltages and allow for highly efficient charging and discharging.
Generally speaking, smart BMS systems that automatically adjust electricity flows are considered premium features and designed to protect against possible damage to the system.
Thanks to recent developments, some of the newer lithium-ion batteries on the market make it easier to take complete control of the internal BMS. While some companies use an app (see KiloVault below), others use an onboard LED or LCD screen.
Last but not least, consider the temperature rating of the 12v LiPo battery before making your final decision. If you plan to take your battery into cold weather conditions (in a van, RV or home), it's good to know that your technology can work without putting you in the cold.
There are a few temperature ratings to keep in mind. Namely, batteries have charge, discharge and storage temperature ratings that indicate how they can be used safely while maintaining normal operating conditions.