Everything You Need to Know About Solar Batteries

Best Company Editorial Team

Last Updated: January 25th, 2023

By Jenna Vasquez and Kaitlyn Short

If you’re in the market for solar, or think you might be someday soon, chances are you want to know the ins and outs of solar batteries, how they work, and how they can pair with a solar system.

Luckily, we’ve got you covered. In this article, we’ll go over everything you need to know about solar batteries, from lifespan and types of batteries available to how solar batteries work and what they cost. 

There are many benefits of adding a solar battery to your solar system, which we’ll discuss in greater detail below. Check out our quick links to get your questions answered, or read on for a full overview of solar batteries.

  • What are the most common types of solar batteries?
  • How long do solar batteries last?
  • How does a solar battery compare to a regular generator?
  • How do solar batteries work?
  • How much do solar batteries cost?
  • What are the benefits of solar batteries?

Types of solar batteries

While there are a few different types of solar batteries, most homeowners will be interested in the most popular type — a lithium ion solar battery.

Lithium ion batteries

Lithium ion batteries are used in a variety of consumer electronics and electric vehicles because they are typically very reliable, long-lasting, and maintenance-free. This also makes lithium ion a great choice for a solar battery.

Lithium ion solar batteries have a high energy density compared to other solar battery types. This means they can hold more energy in a smaller space and don’t take up as much room in your home or garage. 

Most lithium ion solar batteries also have at least a 10-year warranty, so they last a long time. The best solar batteries are the ones you rarely have to think about, and lithium ion definitely fits the bill. 

Because of these great perks, lithium ion batteries do tend to cost more than other energy storage options for your home. However, for many homeowners, the benefits of lithium ion batteries far outweigh the cost associated.

Check out these top-rated solar companies that also offer lithium ion batteries:

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Other solar battery types

While they are the top choice for many homeowners, lithium ion batteries are not the only type of solar battery on the market today. Other types of solar batteries are ideal in more niche situations, but if you find yourself in need of a lithium ion alternative, you may be able to take advantage of one of the options below.

  • Lead acid batteries — These are the oldest type of solar battery on the market and also the cheapest. Lead acid batteries are ideal for people living off the grid or looking for an emergency backup power option, but remember that they will require regular maintenance and ventilation.
  • Nickel based batteries — These are a durable yet toxic battery often used in the aircraft industry or for other large scale projects. Homeowners probably won’t choose this type to go in their garage, but if you have a large scale project concerning solar, they may be something to look into.
  • Flow batteries — These are a large, yet energy efficient and long lasting solar battery option, ideal for large-scale projects. Because of their size, these solar batteries are quite expensive. Again, these aren’t an ideal choice for a private residence, but do have uses for larger installations.

Solar battery lifespan

Solar energy batteries typically last between 5 and 15 years while a solar panel system usually lasts 25 to 30 years. This means you’ll need to replace your battery (or batteries) at least once during the lifetime of your panels. The lifespan of a battery typically depends on the type of battery, where your battery is stored, and how often you use the battery. 

Type of battery

Lithium-ion batteries have the longest lifespan. They also have the best storage capacity and depth of discharge (DoD) – the percentage of available energy relative to the battery's overall capacity. 

Lithium batteries are often the most expensive option but usually provide the most value. Other types such as lead-acid, nickel based, and flow batteries have a lower DoD, require frequent replacement, and need routine maintenance. 

Location of the battery 

Solar batteries perform best when kept in a temperate climate. Your battery may last longer if kept in a garage or a place with a controlled temperature. 

In hotter surroundings, a solar battery has to work harder to maintain efficiency. Hot weather puts added strain on the battery and may impact the overall lifespan if exposed for long periods. If the battery is exposed to extremely cold temperatures, the electrons slow down and the battery drains faster.

Battery usage 

You might notice that your phone battery drains faster the older it gets. Just like a phone battery, a solar battery has a limited number of battery cycles and slowly loses storage capacity. 

The more often you use your solar battery, the shorter its lifespan will be. A solar battery used just for emergency blackouts will last longer than one used every night. 

Paying attention to the depth of the discharge will also increase the lifespan of your battery. To maximize your battery’s lifespan, read the manufacturer’s recommendation for your battery type and avoid draining your battery past the DoD. 

Solar battery backup vs. regular generators

One possible alternative to solar battery storage is gas powered generators. Generators typically cost $800 to $20,000 with installation depending on the size and brand. People in areas with unpredictable weather or frequent power outages might buy a generator to keep their homes running during power outages. 

We’ve created a quick chart comparing a gas-powered generator vs. a solar battery backup. For simplicity, we will compare a residential solar lithium battery to a 26kW home standby generator. 

  Solar lithium ion battery Standby generator
Cost Starts at $7,000 Starts at $6,000
Lifespan 5 to 15 years 25 to 30 years
Best warranty available 10 years 5 years
Environmental impact Runs on renewable energy Emits carbon monoxide
Size Fits on the wall Needs about 50 sq ft 
Possible long-term savings Save up to $1000 per year No energy savings
Tax credits available Yes No
Requires routine maintenance No Yes (Every 6–12 months)

How solar batteries work

The basics of how solar batteries work with a solar system are pretty straightforward. Essentially, your solar panel system on your roof produces energy to power your home utilities. 

Any excess energy produced by your system can either go back to the public utility grid or into your personal solar battery. To learn more about energy going back to the grid, you can read up on net metering.

When you have a solar battery installed, energy from the sun hits your panels as direct current (DC) electricity and flows through an inverter to become alternating current (AC) electricity. This AC electricity powers your home appliances during the day while the sun is shining.

The extra electricity produced during sunny days gets stored in your solar battery and essentially recharges it. That way, in the evenings or on a cloudy day, your home appliances will be powered by the energy in your solar battery, rather than you having to “borrow” energy from the public electricity grid.

In this way, solar batteries work as a backup power source when your panels aren’t actively producing electricity, either due to it being nighttime, cloudy, or a power outage affecting the grid and your solar system.

Energy storage cost and financing

Residential solar battery storage options cost anywhere from $300 to more than $20,000. You will also need to pay for installation, which typically costs between $2,000 and $4,000. 

Lithium ion batteries are the most expensive type of battery, costing between $7,000 and $30,000. Lead acid batteries are usually about half the price of lithium ion batteries but require more maintenance and don’t last as long as lithium batteries. 

Factors that affect the cost of the battery include energy capacity, power, chemistry, warranty, installation company, and depth of discharge. 

Will a solar battery save you money?

The truth is most people won’t save money by installing a solar battery. Solar batteries are expensive to install and don’t last as long as solar panels. If you are able to utilize your battery on a time-of-use rate or sell back extra electricity to the grid, you may be able to save around $500–$1,000 per year. 

Battery storage savings tips

If you live in an area offering net metering and time-of-day electricity rates, you may save money by adding battery storage to your solar panel system. However, even these factors do not guarantee savings. You need to be smart about how and when you use your solar battery backup. 

Here are some tips to maximize cost savings: 

  • Run optional large appliances during off-peak hours. This could include your air conditioner, heater, pool pump, EV charger, dryer, dishwasher, etc. 
  • Aim for a fully charged battery at the start of the peak electricity period. You can then choose to use your battery this time or sell back energy to the grid at the best rate. Try to buy electricity from the grid when it’s low and sell it back when it’s high.  
  • Adjust your backup battery reserve depending on the weather and time of year. Your battery should always have a 20 to 30 percent charge. If you are preparing for a storm, winter, fire danger, or a public safety power shut-off, you can increase your backup reserve to ensure you have enough energy during a power outage. 
  • Find a good electricity rate plan. If your area has a time-of-use option, consider switching to that electricity plan to reserve battery use for peak hours. 

Solar battery financing options 

Customers can typically choose between a cash purchase, loan, or lease when buying a solar battery. 

  • Cash purchase The most common way to buy a solar backup battery is to pay for it upfront, which can help you maximize battery savings. You’ll get to take advantage of any incentives and rebates offered for solar storage. This may not be feasible for everyone because of the high cost. 
  • Loans — You can either include the solar battery in your solar panel system loan or get a separate loan for just the battery. These loans are available through solar lenders, home-equity lenders, banks, and credit unions. 
  • Lease — A solar battery lease is much rarer than a cash purchase or loan. If you are already leasing a solar panel system, you can ask about adding battery storage. This increases your lease payment slightly but gives you added peace of mind during inclement weather. 

You can learn more about solar financing options here

Benefits of adding a solar battery

Some of the benefits of adding a solar battery have been discussed throughout this article, but in a succinct way, here are some perks of including a solar battery as part of your solar panel system:

  • Store excess energy your system produces
  • Avoid losing power during temporary outages
  • Reduce your carbon footprint by avoiding using the grid
  • Provide sufficient energy for your home even when dark or cloudy

If you can afford it and have the space to install a solar battery, it’s a great option for homeowners who are considering or already have a solar system installed.

Get started with solar storage

As more and more homeowners make the switch to solar, solar batteries are likely to increase in popularity as well. If you want to include a solar battery in your home solar system, check out top solar installers in your area that offer battery storage solutions.

Check out top solar companies offering solar batteries.

Picture of Sunrun logo offering Brightbox battery. Click for link to get quote. Picture of Sunpower logo offering SunValut Battery Storage. Click for link to get quote. Picture of ADT Solar logo offering enphase and Tesla storage. Click for link to get quote.
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