solar panels used on a house in the mountains.

Lithium Solar Batteries: A Guide For Homeowners

Aug 25, 2022

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Lithium solar batteries are offering homeowners with solar panels the flexibility to stay connected to the grid or even take their home completely off the grid. While lithium solar batteries aren’t the only type of batteries compatible with solar panels, they have some characteristics that make them the top-selling choice.

Let’s take a look at why so many people – from homeowners to developers – are choosing lithium batteries.

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Why Homeowners Want Solar Batteries

Many homeowners are turning to solar power to avoid rising electricity costs. But here’s what people new to solar might not realize: Going solar may not entirely eliminate your utility bills.

In many cases, utility companies charge “grid-tied” solar-powered homes – which are the majority – for being connected to the grid and using electricity during periods of high demand. The connection fee is to cover maintenance for using the grid as a battery. Utility companies may credit solar homeowners through a billing method called net metering.

It’s not possible to reduce the connection fee. But solar energy storage can help avoid fees for electricity consumption during peak hours. Here’s how it works as part of a hybrid solar system:

  • During the daytime when your solar array might produce more power than you consume, your battery bank will store excess energy.
  • The battery can then power your home during peak hours when rates are highest, saving you from paying a higher per kilowatt-hour charge. Batteries are also useful at night and during outages.

The Solar Energy Industries Association (SEIA) projects that by 2025, nearly 30% of new solar systems will be paired with energy storage. As of 2021, barely 11% of systems included energy storage.

Another Benefit Of Solar Batteries

Most solar-powered homes don’t stay powered up during a blackout. They automatically shut down to avoid adding power to the grid. This is to prevent utility line workers from being injured while working to restore power.

Configured correctly, backup batteries can be used to power a home during a blackout, which is highly beneficial if your local utility grid is unreliable.

What Are Solar Lithium Batteries?

A few types of lithium battery chemistries exist, including lithium-ion and lithium iron phosphate. Overall, the different types feature similar characteristics.

Lithium batteries have a wide range of uses, from cell phones to electric cars to airliners. This battery chemistry has been around since the 1970s and was instrumental in making electric cars more viable. The solar industry noticed how well the technology would apply to storing solar energy.

Here’s what lithium batteries offer solar homeowners compared to other types of batteries:

  • No maintenance
  • More usable storage capacity (called depth of discharge)
  • Longer life
  • Better efficiency, meaning homeowners get a higher percentage of energy out of lithium-ion batteries than other battery types with the same amount of input
  • More energy density, allowing a smaller battery to hold more energy

These advantages come at a higher price than other batteries, though.

How Long Do Solar Lithium Batteries Last?

It’s common for lithium-ion batteries for solar energy storage to have warranties covering 10 years or 10,000 cycles – a cycle being a complete charge and discharge.

Some lithium batteries have lifespans that outlast the warranty. One of the major manufacturers, sonnen, is known to have batteries that last longer than 20 years. In fact, one master-planned community in Arizona equipped its solar-powered homes with sonnen batteries to create a virtual power plant.

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What Do Lithium-Ion Solar Batteries Cost?

It’s difficult to assign a particular cost to lithium batteries. Generally, lithium batteries will be cheaper when included as part of a newly built solar energy system, as opposed to when they’re added to an existing solar system. Existing systems may need new inverters, adding to the cost. Still, it’s possible to get a general idea of the cost.

By themselves, the batteries typically range from $150 – $210 per kilowatt-hour (kWh) for smaller solar installations like home photovoltaic (PV) arrays. This doesn’t include the cost of other hardware such as a battery management system (BMS) or solar charge controller for off-grid homes. 

The prices per kilowatt-hour don’t include other hardware, software or labor. Neither do the costs reflect potential credits and rebates you might get from government agencies or utility companies.

According to the U.S. Department of Energy, adding batteries to an existing system can cost anywhere from $12,000 to $22,000.

What Are The Alternatives To Lithium Batteries For Solar Energy Systems?

Lead-acid batteries, similar to the 12-volt batteries you probably have in your car, are another option for homeowners with solar panels. They’re cheap, and nearly every part of them can be recycled.

Lead-acid batteries come in two varieties: flooded lead-acid (FLA) and sealed lead-acid (SLA). The unsealed are like the older type of 12-volt batteries in most cars, while the sealed ones are more like the newer generation of absorbent glass mat (AGM) and gel batteries.

The FLA batteries require maintenance such as water refills every 1 – 3 months. They also emit gas, which requires proper ventilation.

Sealed lead-acid batteries handle a variety of temperatures well and don’t require maintenance. They won’t spill since they’re sealed. These characteristics make them an attractive option if you have an off-grid property that you rarely visit.

Best Batteries For Solar Energy Systems

Two main options are available for home solar energy storage. Lithium-ion batteries account for the largest share of the solar battery market, while the market for lead-acid batteries is considerably smaller and mainly focused on smaller off-grid applications.

But does that make lithium-ion batteries the best choice for solar?

Lithium Batteries Versus Other Batteries For Solar Energy Storage

So which solar battery type is best for your home? For most situations, lithium batteries offer the best performance and past battery life. FLA batteries can be a solid choice for people who enjoy hands-on projects like maintaining batteries, while AGM batteries or gel batteries can be a smart pick for off-grid vacation homes.

Battery Type

Energy Density

Lowest Maintenance

Lowest Price

Longest Lifespan

Lithium

 

Flooded Lead-Acid

 

 

 

Sealed Lead-Acid

 

 

 

 

Vehicle To Grid: A Future Option For Lithium Batteries

From 2016 – 2021, homeowners went from 40,000 megawatts of solar capacity to 120,000 megawatts of capacity. In that same time, electric vehicle sales soared from 200,000 megawatts capaity to 600,000.

Here’s the connection: Electric cars carry huge banks of lithium batteries. Vehicle-to-grid (V2G) technology is being developed that would allow your solar panels to use an electric car as an energy storage system.

The solar panels would charge the car during the day when electricity demand is lower, and then feed energy back into the grid during peak hours. The technology could also allow an electric car to power a home during a blackout.

V2G is still in its early stages, but the technology has the potential to expand storage for renewable energy, stabilize power grids and reduce energy costs.

The Bottom Line

Lithium batteries offer longevity, ease of use and the highest energy density. These benefits make them a great choice in many applications.

Are you concerned about rising utility costs or unreliable costs? If you’re interested in a grid-tied solar panel system with battery backup power, get started today!

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