Which are the best battery systems for an off-grid home? As of 2020, lithium-ion is the best choice when it comes to off-grid battery systems. This is due to it's longer life span, more efficient storage of energy, and deeper discharge rates.
Lithium-ion batteries are not the most affordable, but over the long run, they have a higher return on investment compared to lead-acid batteries. Choosing the best battery system will come down to your specific needs, your budget, and your usage.
Most places assume that readers have a working knowledge of batteries, but if you are new to off-grid living there’s a good chance you’re unfamiliar with the battery system basics for an off-grid home.
Before we explore which battery options are best, let’s learn some battery basics.
In simple terms, a battery is just a place used to store energy that has been acquired through generators, solar power, wind power, or even hydra power. The battery system is an integral part of any off-grid home as it can help supplement drops in the electric generated by your off-grid system and it can also be a vital backup system in case any of your power generating systems fail.
The size and demand of your battery system will depend on the types of renewable energy solutions you are utilizing in your off-grid home. If you're combining solar panels with wind turbines and water turbines, you will be relying less on your battery system to provide the necessary power needed to run your off-grid home.
A battery system comes in handy when if your only source of power is from solar and you will be needing electricity at night or on cloudy days. Even if you have other forms of renewable energy generation such as wind or water turbines, it's always smart to have a backup.
This allows your power to run longer without having to replenish. This is an important feature for batteries when you are living off the grid. If you are planning to run an appliance like a dishwasher or dryer in your off-grid home during the colder months, then you’ll be depending on your battery system to provide power.
The sad truth is that not many areas have a consistent balance of daylight, nightfall, cloudiness, clear skies, and temperature on a daily, weekly, monthly, or yearly basis. The seasons are constantly changing and since off-grid homes rely on the weather to generate power, there can be major inconsistencies.
Click here for a handy battery bank calculator. It will help you determine how large your battery system should be for your off-grid home.
It’s much easier to establish a system with a good balance of available power when there is a battery system supporting the chosen energy system.
Lithium-ion batteries are one of the most common storage technologies. There are three types: pouches found in smartphones, cylindrical found in power tools, and prismatic found in electronic vehicles. Prismatic shapes typically have applications in solar energy storage, specifically lithium iron phosphate (LFP) batteries.
These batteries are estimated to cost around $578 to $950 per kWh which exceeds the cost of lead-acid batteries. The additional cost of this option stems from the need for a battery management system that monitors the voltage and temperature of each cell. Lithium-ion batteries are known to deliver more cycles in their lifetime than lead-acid which makes them a better choice for applications when batteries are cycled in order to provide ancillary services to the grid.
The most beneficial part of this battery is its high charge and discharge efficiencies which help to harness more energy. These batteries do not require refills and maintenance and are fairly light, so they are easy to install and replace.
Organic-based batteries are free from toxins, so they are easier to dispose of. Inorganic batteries are much more difficult to dispose of due to its toxicity. To dispose of this battery correctly, there is often an associated cost.
Deep cycle, lead-acid batteries have been a fixture in renewable energy and reliably used in many off-grid homes for decades. These batteries typically cost much less than lithium-ion and are one of the more cost-effective options. These batteries include absorbed glass mat (AGM) and gel models.
Many AGM batteries on the market today are built for dual-purpose or standby options like emergency backup but not deep cycling. However, Newer deep cycle AGM designs have allowed performance and total energy input to increase significantly, making them a great choice for renewable energy and at a much lower price than gel batteries.
A number of factors contribute to battery life including ongoing maintenance and initial design. This means it can be hard to tell when batteries will need to be replaced. Flooded lead-acid batteries need to be replaced regularly while AGM and gel technologies do not require maintenance due to its recombinant nature.
This means they can operate over long periods of time without maintenance. Disposal for this type of battery is important due to its toxicity. Luckily, the automotive industry has organized for lead to be recycled very early on.
Flow battery use has significantly increased with time. Most flow batteries use two electrolyte liquids: one with a negatively charged cathode and one with a positively charged anode. The cathode and anode are separated into two tanks so that they will not come into contact causing the battery to short.
This can happen fairly often with lithium-ion batteries. Flowing into the battery is the exchange of negatively and positively charged fluids, which produces the electrical current without degradation. This means a longer cycle life. When you consider the cost of storage over time, flow batteries often succeed due to their ability to last decades with little maintenance.
Since the flow battery’s membrane degrades little over time, it does not need much maintenance and does not need to be replaced for decades. Adding more batteries can increase storage hours as well as simply adding electrolytes. This battery has no cycling limitations and the batteries can be charged and discharged without affecting their performance. These batteries are less reactive and fairly easy to dispose of.
Nickel-cadmium or NiCd batteries have been around since the 1900s. Although they haven’t benefitted from advanced technology, they are a simple yet reliable option that provides long life. This option is very inexpensive. NiCd batteries are vented which allow gases to dissipate.
They used to require some watering, but new designs allow the gases to recombine into water making it nearly maintenance-free. This coupled with its durability in extreme temperatures makes it perfect for off-grid homes in harsh environments. These batteries have a high life cycle, lasting up to 20 years.
Since Cadmium is a hazardous material, it needs to be extracted before the battery can be recycled. The Nickle can then be recovered and used to make stainless steel.
If you have the budget and you're looking for a long-lasting and low-maintenance solution, it's best to go with a lithium-based battery system for your off-grid home. If you're trying to save money upfront and you live in a mild climate, you might consider a modern lead-acid battery system.
Consider the types of power generating systems you'll be using in your off-grid home. If you're utilizing wind and water-based turbines, you'll be generating power 24/7 and won't need as large of a battery system than if you were just using solar alone. Do you have experience with off-grid battery systems? We would love to get your input in the comments below.