How Long Do Solar Panel Batteries Last? (+ Make Them Last)

If you’re wondering how long do solar panel batteries last, you’re not alone. Many solar panel owners consider installing a battery at some point. That way, they can use the power they collected all day when they need it most, like during a power outage. 

Typically, solar power batteries last between 5 and 15 years. That means you’ll likely have to replace your battery at least once during the 20 to 30-year lifespan of your solar power system. 

If you’re considering a solar panel battery to go with your solar power system, though, there are probably several other things you need to know. Below, we’ll discuss: 

  • The average battery lifespan and factors that make it longer or shorter
  • How long a solar power battery can power your home
  • The cost of replacing a solar power battery
  • How to maintain your solar power battery 

By the time we’re done, you’ll know everything you need to know about solar power batteries. You’ll also know whether installing one is worth the price you pay for it. Keep reading.

Solar panel batteries connected

What’s the Average Lifespan of a Solar Panel Battery?

The average lifespan of a solar panel battery varies significantly between 5 and 15 years. That’s a pretty big range! The lifespan of the battery you choose will depend on three things:

  • The battery type
  • Usage
  • Environment 

Most manufacturers will provide a warranty that gives a minimum guaranteed lifespan for that particular battery. However, your battery may last far longer than the warranty states, depending on type, usage, and environment. 

Battery Type

Batteries come in three different types: lead-acid, lithium-ion, and saltwater. Each type has its pros and cons, but most residential solar power system owners rely on lithium-ion batteries. 

Lithium-ion batteries are small and light. They offer a relatively long lifespan, depending on how you use and store them, and have a higher DoD. 

DoD refers to Depth of Discharge. It’s the amount of power a battery can discharge relative to its full kWh capacity. 

In other words, if you have a 10 kWh battery, which is typical, and you use 7 kWh of its charge, the battery’s DoD is 70%. 

Manufacturers recommend a specific DoD for the batteries they sell, and going below it can negatively impact the battery’s lifespan. So, a higher DoD, like lithium-ion batteries offer, is ideal. 

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Solar Panel FAQ Video

Lithium-ion batteries can also handle extreme temps and are coming down in price. They used to be very expensive, but thanks to high demand and technological advances, lithium-ion batteries are relatively affordable. 

Still, they’re not as inexpensive as lead-acid batteries. Lead-acid batteries were the most popular solar power battery option for decades. Unfortunately, they feature a short lifespan, low DoD, and can’t handle extreme temperatures. 

Saltwater batteries are the new kid on the block. They have the advantage of using no heavy metals. This makes them environmentally friendly and easy to recycle. They also have a long lifecycle, similar to lithium-ion batteries. 

Unfortunately, saltwater batteries are bulky and difficult to manufacture at scale. That makes them hard to find, and if you can find them, they may be expensive. 

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That said, if saltwater battery manufacturers can overcome production problems, they may end up being the least expensive battery option with the best lifespan. Unfortunately, they’re just not there yet. 

Usage

Have you ever noticed that a brand new phone can hold a charge for a day or more, but as it ages, the amount of charge it holds seems to be less and less? You’re not imagining it. 

The more often you charge and discharge any battery, the less time any one charge will last. 

In fact, usage is the biggest determining factor in solar panel battery lifespan. So, if you have an off-grid system that you use every night, your battery will have a relatively short lifespan, closer to 5 than 15 years. 

Conversely, if you have a grid-tied system that only uses the battery in the event of an outage, you can expect the battery to last much longer. 

You can increase the lifespan of your solar panel battery by paying close attention to the manufacturer’s suggested DoD. If you don’t push the battery beyond that recommendation before recharging, you can expect a longer lifespan. 

Environment

Solar panel batteries last longer in temperature-controlled and sheltered environments, like a basement or garage. 

That’s because hot and cold temperatures change the rate of chemical reactions within the battery. 

In hot temps, chemical reactions happen faster, which increases the rate of wear and tear on your battery. In cold temps, reactions slow down, which causes the battery to drain faster. 

Lithium-ion and saltwater batteries can both put up with pretty big temperature swings, but putting them in a sheltered environment will still increase their lifespan. 

Lead-acid batteries, though, are very sensitive to temperature changes. Anything below 40 or above 80 degrees Fahrenheit will significantly decrease their lifespan. 

How Long Can a Solar Panel Battery Power Your Home? 

How long a solar panel battery will power a home depends on the battery’s capacity and the home’s power consumption

Solar panel battery capacity is measured in kilowatt-hours (kWh). Most batteries vary between 1 kWh and 10 kWh or more, but 10 kWh is the average capacity for most residential solar panel batteries. 

That said, if your home is large or you have increased power needs, you may opt for a larger battery. Or, you can link multiple batteries together to create more capacity. 

Kilowatt-hours aren’t equal to hours in a day, and in some homes, 10kwH will last through the night and then some. In other homes, 10 kWh won’t last long at all. It all comes down to the home’s energy consumption. 

In the event of a power outage, when you need to rely on your solar panel battery, you’ll probably be able to reduce your energy consumption and increase the amount of time your battery’s charge will last. 

You can do this by turning off lights and not charging devices like laptops or cell phones. You may want to keep your TV, dishwasher, and other appliances off as well. 

Still, there are some things that you’ll need to keep powered, like your refrigerator. If you have an energy-star compliant fridge, you can expect it to use somewhere between 1-2 kWh per day. 

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If you have an electric water heater, you’ll probably want to keep that running as well. Water heaters tend to use about 5 kWh per day. 

Ideally, you’ll be able to refrain from using bigger home systems like your AC. However, in very hot climates, that might not be feasible. Unfortunately, ACs cost about 1.5 kWh per hour of use. 

So, if you had to run your fridge, your water heater, and your AC for a couple of hours, you’ll reach the 10kWh capacity of most solar panel batteries within a day.  

What Do Replacement Solar Panel Batteries Cost? 

Solar panel battery replacement costs can vary significantly, from as little as $300 to as much as $15,000. The differences in cost depend on the capacity of the battery you need to replace, the battery type, and the installation requirements. 

However, on average, the cost of a replacement solar panel battery is $6,000. 

Given that you’ll need to replace solar panel batteries at least once throughout the lifespan of your solar power system, it’s crucial to understand what affects the cost of replacement. 

When it comes to capacity, you can expect to pay anywhere from $400 to $750 per kWh, depending on the battery type. On top of that, you can expect installation fees of $2,000 to $3,500.  

In general, lithium-ion batteries are the most expensive to replace, with costs averaging around $7,000 or more. Depending on the battery capacity you need and installation requirements, a Li-ion battery could cost upwards of $30,000. 

Lead-acid batteries are less expensive, averaging around $5,000 to replace. 

In theory, saltwater batteries would be the least expensive to replace, with some startups claiming they can produce them for as little as $2,500. 

Unfortunately, those startups have yet to produce a product at scale. That means, if you can find a saltwater battery, it will probably cost more than the lithium-ion option. 

How Do You Maintain a Solar Panel Battery? 

Maintaining a solar panel battery has a lot to do with where you place it. 

The National Renewable Energy Laboratory (NREL) suggests putting solar panel batteries in a cool, dry place with sufficient spacing between units. 

Garages tend to work well, as long as there aren’t any fire hazards around. Though solar panel batteries have come a long way in the last few decades, there’s still a non-zero risk of explosion if you have a house fire.  

If you have multiple battery units, make sure there’s ample space between them. That will allow for cooling and easy maintenance check-ups. 

During a maintenance check-up, a professional should come out and check for any fluid leaks. You can also identify these yourself if you see substances accumulating around the outside of your battery. 

You should also avoid pushing past the manufacturer’s suggested DoD when running your batteries. If you find that that’s happening with any regularity, consider investing in a battery with a bigger capacity. 

Sources: 

Solar Panel Batteries FAQ

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