The Best Batteries for Off Grid Solar Power Systems
Solar panels are a marvel of modern technology that makes going off grid possible, but they wouldn’t be practical to use for energy independence if it wasn’t for one crucial component: batteries. Even in the sunniest states, the sun simply doesn’t shine all the time. Unless you are willing to go without power on cloudy days or at night, you will need batteries to store excess energy so that you can keep the lights on (literally) when there is no sunlight.
In this article, we'll talk about the best batteries you can buy for your off grid solar system and how to evaluate different batteries. If you aren’t that interested in learning about solar batteries and what makes them so important in your off grid solar system, you can skip right ahead to our list of recommended batteries.
What do off grid solar batteries do?
When you go off grid, you need a way to store energy generated throughout the day. With a grid-tied system you can draw power 24/7, but as we all know, the sun doesn’t always shine all the time. So if you use off grid solar power, your batteries need to store enough power to keep you going until the sunlight’s back. Of course, grid power isn’t available all the time either. The grid fails frequently, leading to brownouts and blackouts. Off grid batteries aren't affected by outages so if you want to guarantee reliable power 24/7, then batteries are the right choice.
To avoid being left in the dark (literally), you need a battery so that you can access stored energy no matter what’s happening outside.
What makes a battery the best?
So, what makes a battery a good battery? There are a few things you need to consider when choosing your solar battery:
Let's face it: solar power systems are expensive (although there are ways to make it very affordable). You might be tempted to cut costs wherever you can by buying a lead-acid battery. We don’t recommend it, however. While the initial cost is lower, the lifetime value and quality offered by lithium batteries is better in the long run. The batteries we recommend offer superior quality at a great price.
The battery's capacity measures the amount of solar power that can be stored and then discharged. Usable capacity varies between batteries and manufacturers, but in general, your lithium battery has a higher energy density than a lead acid battery. The best batteries are the ones that can meet your storage needs in an efficient and cost-effective way. You can store more solar energy in a lithium battery with the same size and shape as a lead acid battery.
Depth of Discharge
The depth of discharge refers to the amount of solar energy that can be drained from the battery without damaging its internal functioning. Think of it as the capacity that you can use before you need to recharge your battery. You can safely drain 80-85% solar energy from a lithium battery, compared to around 50% for a lead acid battery, when using your solar panel system. When you are shopping for a solar battery, you want something with a high discharge rate so you make the most of the energy stored inside it.
Efficient Power Usage
Efficiency refers to the percentage of electricity that is put into storage to be used later. It’s inevitable that you will lose some kWh of electricity when you convert power from DC to AC electricity and when you store electricity in your battery and use it again. The higher the efficiency, the less energy you lose in the storage process. Most lithium batteries have an efficiency of around 95%, which means you can use most of the energy stored.
Just like solar panels, battery performance declines over time. We measure the lifetime of batteries in cycles. Every time you discharge a battery to power your home and recharge it with solar energy, it counts as a cycle. Your battery should last for around 5000-7000 cycles in an average 10-year lifespan.
Lead-acid solar batteries were used in early solar power systems. They have a shorter lifespan, lower depth-of-discharge, and require regular maintenance, which is why they aren’t the preferred option anymore. Lithium-ion batteries have a longer lifespan, require very little maintenance, are more lightweight and smaller. They have become popular among residential home owners, and have been improved parallel to developments in electric car battery technology.
If your solar provider doesn't recommend lithium-ion batteries to you, then you should find another provider for exactly these reasons.
Bells and Whistles
Many battery companies sweeten the deal by throwing in extra bells and whistles that make installation and maintenance a breeze, like wheels, connectors, output plugs, status panels, remote controls, built-in charge controllers and inverters. These added extras can make a big difference when setting up your system!
What are the best solar batteries for off grid power?
Let's take a look at some of the most popular solar batteries for off grid solar applications and how they compare to one another:
We've sung Mammoth RE's praises, with good reason. The Mammoth RE PRO is considered the best solar battery for storage. There’s a lot we love about it, including:
- A large capacity of 23.5 kWh
- Ease of connection using the plug-and-play SB 175 connector
- Safety features including an on/off switch
- Fewer potential points of failure
- Convenience with castors for mobility
And it comes at an extremely reasonable price compared to other solar batteries. Mammoth RE PRO batteries are very easy to connect to an inverter or another battery, which makes it great for scaling up your system in the future.
Reliability matters when you go off grid, and the EG4 Lithium Iron Phosphate battery is as reliable as they come. Its 51.2V (48V) 5.12kWh capacity with 100AH internal BMS is composed of 16 UL listed prismatic 3.2V cells in series, which have been tested at 7,000 deep discharge cycles to 80% DoD. With a 99% operating efficiency, this battery has a long lifespan of 10-20 years and can be fully charged and discharged daily for over 15 years. It comes with a built-in BMS for voltage, current, temperature, and health management and is environmentally friendly and lead-free. With flexible racking options and stress-free battery bank expansion capacity, the EG4 is an excellent choice for renewable energy storage.
SOK Battery's 200Ah model is considered the best 12v lithium-ion battery for solar storage due to its massive storage potential, durable build, and unbeatable price. The battery is rated for 4,000-8,000 lifecycles and comes with a 7-year warranty. However, the high demand for this battery may make it hard to find, and the company's customer support is limited. For those with smaller solar energy systems, SOK's 100Ah 12v lithium-ion battery might be a better option.
Jakiper Battery manufactures 24V and 48V lithium iron phosphate batteries (LifePO4). They are high-quality, very user-friendly off grid solar batteries that are easy to install and maintain. It has a Power key for BMS On/Off, allowing for easy control of the battery management system. The battery's terminals can fit up to 2 AWG wires, making it easy to connect to other components of a solar power system. The battery is lightweight, weighing less than 70% of similarly sized SLA batteries, making it easier to handle and install. Best of all, it's backed by a 10-year warranty.
The Pytes E-Box 48100R is a good option if you want to go off grid. The battery is space-optimized and compact, which makes it easy to install and handle. It's also fairly easy for a DIYer to replace a faulty or damaged cell, which can save money in the long run. The Pytes range is high-performance, providing 5.12 kWh (51.2 volts at 100 amp hours), which is perfect for most off grid systems. The smart battery management system (BMS) makes it easy to keep an eye on operations, from real-time temperature, voltage, and current measurements all the way to complete monitoring and battery life calculations. They come with a ten-year warranty and an impressive 90% depth of discharge, and you'll enjoy peak power for years to come.
BigBattery has made it on a few of our Best-Of lists. The 48V KONG Lithium Battery Bank uses LiFePO4 cells with a BMS and 300A fuse, making it a drop-in replacement for lead-acid batteries in off grid homes and energy storage systems. It offers more capacity, shorter charge times, and longer life. The battery comes with pre-installed Anderson connections and an SB175 Anderson to-ring terminal cable for quick installation to any inverter, charge controller, or bus bar. It's great for DIYers.
The Fortress eVault 18.5 kWh Lithium Battery is an excellent energy storage solution. The battery management system is designed with multilevel safety concepts, including overcharge and overcurrent protection, cell monitoring, and balancing. The built-in LCD display provides essential information about the battery, including voltage, state of charge, power output, and operating status. It's perfect for both grid-tied storage and off grid applications. Additionally, a bank of connected eVault 18.5 kWh batteries can expand your total storage capacity up to 222 kWh, making it a flexible solution for growing energy needs. Overall, this battery is a reliable and powerful option for anyone looking to supercharge their energy storage.
If you have a little cabin in the snowy mountains or a ranch house in the desert, you should take a look at the SimpliPhi Power PHI 3.8-MTM Battery. The battery comes in both a 48V and 24V version, making it suitable for different off grid designs, with a working temperature of -4 to 140°F. It utilizes the Lithium Ferro Phosphate (LFP) chemistry, which eliminates the risks of thermal runaway, fire propagation and operating temperature constraints. You can use your PHI 3.8-M Battery in both off grid and hybrid setups, which is great if you are looking for a little flexibility.
Ark batteries boast impressive specifications that make it a great choice for a variety of applications. Batteries can be safely discharged to 0%, making them a dependable energy source that retains 80% of their original capacity after 5,000 cycles. It charges in less than half the time of lead-acid batteries and is much more efficient, with no loss of discharge power. The battery is lightweight, maintenance-free, and can be installed in multiple positions, with terminals on both the front and back. Additionally, it features field-serviceable internal electronic components, making it easy to replace parts if needed.
Rich Solar's new lithium battery is an excellent choice for those who need a reliable and long-lasting power source. It has a wide operating temperature range and performs well in high temperatures. The battery is also lightweight and easy to maintain, and the built-in smart battery management system ensures that it has a long cycle life capacity. The lifetime customer support is an added bonus, and the battery comes with overcharging or discharging protection, overcurrent and short circuit protection, and high and low-temperature disconnects.
DIY with an off grid solar power kit
Going off grid is easier than ever before with DIY off grid solar power kits. Installing a solar power system with a kit is simple and easy, and it can save you at least half of the cost of hiring a company. These kits contain all the equipment you need, which is the same or better than what solar companies use, custom-tailored to your needs. There are a host of other benefits to a solar kit and with a little bit of knowledge, you can easily set up and install your solar power system yourself.
It might seem daunting, but a quick course can teach you everything you need to know about solar power, including how to install a solar kit yourself. Not only will you save money, but you'll also get the satisfaction of having done it all yourself.
Batteries are an essential part of any off grid system because they allow you to store power for later use. Choosing the right battery is easy once you know what to look for, including lifespan, cost, capacity, and efficiency.
If you'd like to know more, there's good news. There's a handy off grid solar power FAQ and if you really want to become an expert you should take a dive into our guide, Off grid solar power 101.
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