Lithium iron phosphate (LiFePO4) batteries are somewhat new to the solar market, and they are making (energy) waves. Not to be confused with their not-so-distant cousin, the lithium-ion battery, lithium iron phosphate batteries use a similar chemical composition but create several advantages that mean standard lithium ion simply can’t compete.
Let’s learn more about these energy storage systems and see what makes them the go-to power source for solar panels.
What Is a Lithium Iron Phosphate Battery?
A standard lithium-ion battery utilizes an iron cathode to attract electrons from an external circuit. A lithium iron phosphate (LFP) battery’s cathode is phosphate-based, making it more stable chemically and thermally. It does not use any rare metals or battery acid like other battery packs.
The stability of lithium iron phosphate batteries means the user doesn’t have to worry about any battery fires or explosions, even if damage occurs. The batteries will remain stable even if their temperature rises as high as 150°F. LiFePO4 batteries are becoming more popular in various industries. They can be found not only in home solar panel kits but also in smartphones, computers, watches, marine batteries, and electric car batteries.
Benefits of Lithium Iron Phosphate Batteries
Based on their description above, it’s obvious that lithium iron phosphate batteries have significant advantages over standard lithium-ion batteries and lead acid batteries. Besides being much safer, lithium iron phosphate batteries provide numerous benefits to anyone looking to invest in them for solar panels for home use or small solar panel kits.
Less Cell Density
A battery’s cell density refers to how much power it can store in the space it has. The higher the density, the longer the battery can run. Now, you may be thinking, but wait, lithium iron phosphate batteries have a lower cell density, so isn’t that a disadvantage?
In the end, all it means is that to have comparable energy density to lithium-ion batteries, LiFePO4 batteries just need to be slightly larger. And, it’s the lower density that allows lithium iron phosphate batteries to not be at risk of overheating, even if they get overcharged. Because most solar panel installations happen in homes or offices where high voltage is needed, you want to ensure the system won’t pose a threat to anyone nearby. So, LiFePO4 batteries may take up a bit more space, but the trade-off of safety is absolutely an advantage.
Longevity
Another significant benefit of lithium iron phosphate batteries is that their chemical makeup gives them a longer life than any of their counterparts currently on the market. In fact, their cycle life is up to four times longer than standard lithium-ion batteries. This long-life means owners know they’re investing in something over the long term that will save them money and provide peace of mind. In particular, solar energy users won’t have to worry about ending up in a power outage only to realize their battery management system (BMS) has failed due to a dead battery.
As a bonus, lithium iron phosphate batteries are straightforward to maintain, making them a no-brainer when it comes to solar panel maintenance. You can tuck them away almost anywhere and not have to worry about constantly checking on them or if they will become a fire hazard. You can set up your BMS in an attic, basement, crawl space, outbuilding, or anywhere else you see fit.
Environmental Advantages
Many individuals and businesses choosing to go solar desire the environmental benefits these systems provide without fossil fuels for energy. And while it’s true that solar energy is a form of clean, renewable energy, the production and ultimate disposal of batteries is anything but eco-friendly. However, lithium iron phosphate batteries are combating some of these issues head-on.
For instance, even though all batteries contain hazardous materials, making it difficult to dispose of them properly, LiFePO4 batteries are not considered toxic like lead-acid batteries. LiFePO4 batteries are easier to recycle and can also be made from a higher content of recycled materials. Plus, as mentioned, they have a longer shelf-life than other battery types, meaning a user won’t need to go through as many lithium iron phosphate batteries in their lifetime.
Depth of Discharge and Discharge Rate
The delivery capacity of LiFePO4 batteries won’t be affected if they are completely discharged. This feature protects them from damage if they end up fully discharged and makes them an excellent choice for solar energy systems that need multiple batteries. They can discharge at varying rates without concern.
The discharge rate in lithium iron phosphate batteries is also steady and higher than in lithium-ion batteries. This higher rate is beneficial when a solar system tied to the grid needs to take over during a power outage suddenly. The LiFePO4 batteries can respond quickly and manage any power load abruptly sent their way.
Cost
At this point, you may be thinking lithium iron phosphate batteries sound too good to be true, so how much do they cost? While they are the newest batteries to hit the solar market, they are also the most economical option available.
First, the chemicals and materials in LiFePO4 batteries make them cheaper and easier to manufacture because they aren’t as hazardous. Also, the raw materials utilized in production are not as rare as what’s required for lithium-ion batteries, mainly cobalt. By not requiring rare raw materials, lithium iron phosphate batteries become less expensive. And once again, their longer life span makes them more economical as you won’t need to replace them as frequently.
Add it all up, and LiFEPO4 batteries are more cost-effective in the long run than any other option currently available. In addition, as the technology around these deep cycle batteries continues to evolve, they are likely to become even more versatile and inexpensive.
Operational and Technical Specs
Now that we’re clear on all the benefits of lithium iron phosphate batteries, how exactly do they operate, and what do you need to know about their specifications if you want to install one (or more) as part of your DIY solar project?
Let’s go over some general specifications first. With a Renogy LiFePO4 battery with a capacity of 100Ah and a nominal voltage of 12.8 V, you can expect a life cycle of 2,000 with the depth of discharge at 80%. Because these batteries can’t overheat, it’s possible to run them at 100% DOD as well. They have a maximum continuous charging current of 50 A and a maximum continuous discharging current of 100 A.
You can connect them in parallel with up to eight units in total, making them highly desirable for larger solar setups. Plus, when you create a parallel connection, the battery’s auto-balancing function improves the battery’s average charging efficiency in the long term.
Renogy also ensures their LiFePO4 batteries are IP65 water-resistant, making them a reliable choice for RV, marine, and tiny home solar systems. They are also about half the weight of lead-acid batteries of the same capacity, making them easier to transport and store.
The time it takes to charge a LiFePO4 battery varies, but you should plan on about a day just to be safe. Keep in mind that once the battery is fully charged, it can hold that charge for a prolonged period. That means you don’t really need to worry about waiting around for it to charge regularly.
When it comes to operation, you’ll want first to connect any batteries you plan on running in parallel by using battery interconnect cables to connect the positive terminals together as well as the negative terminals together. Keep in mind that you need to use batteries from the same manufacturer and the same model with paralleling. You should also avoid too large of a voltage difference. Lithium iron phosphate batteries could trigger over-current protection if they aren’t connected properly in parallel, even with their auto-balancing functionality.
Next, you can use tray cables and inverter cables to connect the charge controller and inverter on opposite ends of the battery. At this point, you’ll want to switch the battery from “shelf mode” to “active mode.”
For our new Bluetooth LiFePO4 batteries, you’ll also want to connect your Bluetooth module to the up port of your battery (or the first battery in your parallel). Once you pair your Bluetooth module with the DC Home app on your smartphone, you can monitor the battery bank remotely.
The Future of Energy Storage Now
Lithium iron phosphate batteries may seem futuristic and aspirational in their features and functions, but the future is already here. LiFePO4 batteries provide a slew of benefits that outrank any other solar battery choice on the market, from lasting longer to being more environmentally friendly. They are easy to use and maintain and can be paralleled to produce even more storage capacity for larger solar setups. So whether you need one or eight, lithium iron phosphate batteries are a worthy investment to take your solar energy needs to the next level.
