You probably already know that solar batteries let you store extra energy for later use, whether it’s for nighttime or during power outages. But when you start looking into energy storage options, you’ll quickly realize a variety of solar batteries out there. And, like most homeowners, you might find yourself wondering: “Which one is the best fit for my home?” In this article, I’ll guide you through the different types of solar batteries so you can make the right choice. I’ll also touch on other important comparisons to help you better understand what’s out there.
Types of Solar Batteries for Homes
When we talk about solar battery types, we’re really talking about battery chemistry – the materials inside the battery that determine its performance, lifespan, and efficiency.
Lithium-ion batteries
Lithium-ion batteries are today’s standard for home solar storage.
These batteries use lithium-based compounds in their electrodes and an electrolyte solution that allows efficient ion movement. With lithium’s high electrochemical potential, they have a high energy density – meaning they can store a lot of power in a small space.
And that’s good news for homeowners without extra storage space or those who simply want to make the most of the space that they already have.
But apart from space efficiency, here are other reasons why they’re perfect for home use:
- They’re lightweight and compact, making installation easy, even on walls.
- They have a high depth of discharge (DoD), usually 90% or more. So, you can use almost all of the stored energy without any issues.
- With proper use, most last over 10 years without the need for frequent maintenance.
Lithium-ion batteries aren’t a single type, though.
You’ll come across different subtypes, such as LiFePO4 (Lithium Iron Phosphate), NMC (Nickel Manganese Cobalt), and LCO (Lithium Cobalt Oxide), among many others.
If you have to choose among these, go for LiFePO4. It has the longest lifespan and can resist thermal runaway – a dangerous chain reaction where overheating leads to fires. In other words, it has zero fire risks, making it safe and reliable for home use.
NMC and LCO may have higher energy densities, but they degrade faster and are more prone to overheating.
As with anything, lithium-ion batteries have a drawback – cost. You’ll be looking at an upfront investment of at least $9,000 for a unit, which isn’t exactly small change.
Lead Acid Batteries
Lead-acid batteries are a much older technology that was once the standard for solar storage. They still work for a lot of applications, including DIY solar setups, but they’ve been largely replaced by lithium-ion.
Why? First, lead-acid batteries have a shorter lifespan, typically lasting five years or less. They require frequent maintenance, as water levels inside must be checked and refilled. Additionally, they take up significantly more space and are much heavier.
And the list doesn’t stop there. Lead-acid batteries need to be charged more often, and their depth of discharge is lower, meaning you get less usable energy
That said, they do come at a lower upfront cost, around $5,000. But when you factor in the maintenance and drawbacks, lithium-ion is definitely the better investment.
To be fair, lead-acid batteries aren’t entirely obsolete and, as I said, are still widely used today.
Car batteries, for example, are made of lead acid. They’re great at delivering short bursts of energy, which makes them ideal for starting engines. This very characteristic makes them less suited for solar applications where energy needs to be processed over sustained periods.
One advantage they do have over lithium-ion? They can handle a wider range of temperatures, including extreme cold, where lithium-ion struggles.
Are there Other Types of Solar Batteries?
Yes. Beyond lithium-ion and lead-acid battery types, there are a few other battery types. However, they aren’t particularly suitable for homes.
Nickel-cadmium (Ni-Cd) batteries exist, but they’re used primarily in industrial or aviation applications. One major reason for this is that cadmium is highly toxic, making it dangerous for residential use.
Two interesting developments in solar battery technology to keep an eye on, however, are saltwater batteries and flow batteries.
Both solutions use non-toxic electrolytes, making them safer and more environmentally friendly. Even so, in their current state, saltwater batteries don’t yet match the energy density of lithium-ion, while flow batteries require large tanks that aren’t practical for home installation.
Only time will tell when these solutions will be perfected for mainstream use. But for now, lithium-ion still dominates the residential solar battery space.
DC vs AC-Coupled Solar Batteries
When discussing solar battery types, another aspect to consider is how the battery connects to the solar system. This brings us to the DC- vs. AC-coupled comparison.
Unlike our earlier discussion on battery chemistries, which focused on which type is better, this comparison focuses on which battery setup works best for your situation – are you installing solar batteries along with a new solar system, or are you adding one to an existing system?
On one hand, a DC-coupled solar battery connects directly to the solar panels.
The energy flows from the panels into the battery, then gets converted into AC power for use in the home. Since the power isn’t converted multiple times, this setup is slightly more efficient, making it the standard choice for new solar installations.
An AC-coupled battery, on the other hand, connects after the solar inverter.
The solar panels send energy to the home first, and any excess is converted into DC power for storage. Later, when the battery discharges, it converts the stored energy back into AC power.
This double conversion causes minor efficiency losses, but AC-coupled batteries are easier to add to existing solar systems.
Backup vs. Consumption-Only Batteries
Another thing worth discussing is backup vs. consumption-only batteries, which, in a bird’s-eye view, refers to battery types based on function.
A backup battery functions exactly as it’s named – it provides backup power during grid outages, much like a generator. This is how solar batteries have traditionally been viewed by homeowners.
A consumption-only battery, on the other hand, isn’t meant for backup (hence, why they’re also called “no-backup battery”). Instead, it stores excess solar power for later use, primarily to help homeowners avoid drawing from the grid.
At a glance, it seems like consumption-only batteries are pointless because don’t backup batteries serve the same purpose?
The thing is, consumption-only batteries were made for homeowners dealing with unfavorable net metering policies, for example, California’s NEM 3.0 net metering policy, which took effect in 2023.
This policy slashed compensation for excess solar energy sent to the grid by around 75%, meaning homeowners now receive far less credit for their surplus power.
With a consumption-only battery, homeowners can choose the “self-consumption” path, instead of selling excess energy for a much smaller compensation.
And since consumption-only batteries don’t have backup capability – meaning the setup is much simpler – they come at a lower cost, making them a lot more accessible for many homeowners.
Gain Full Control of Your Home’s Energy With Solar Batteries
With Avail Solar, you get a team of solar experts to handle every aspect of your transition to home solar energy – including installing the right solar battery to suit your specific household energy needs.
We only install solar batteries that are proven and sourced from trusted manufacturers. And to ensure you’re making an informed decision, we’ll walk you through the numbers so you can fully understand the return on investment for your purchase.
Request a quote or call us today to speak with one of our solar professionals!