How Long Does a Solar Backup Battery Last?

While solar panels can keep producing power for 25 years or more, backup batteries that store that energy have a shorter lifespan. Understanding how long a solar battery will last, and what you can do to maximize its performance, can help you maximize your investment.

A lithium-ion battery typically comes with a 10-year warranty, but there are steps you can take to help extend its lifespan. Learn how to monitor, maintain, and properly use your battery to ensure you get what you expect in reliable energy security and savings.

How Long Does a Solar Battery Last?

While home solar panels are designed to last 25 or more years solar batteries generally have a shorter lifespan. A typical lithium-ion solar battery is expected to last 5 to 15 years. Many manufacturer’s warranties for batteries are 10 years. If you’re looking at new batteries, you can check a battery’s capacity guarantee which is typically a percentage of remaining capacity guaranteed after a certain span of time. A common capacity guarantee is 70% capacity for 10 years.  

Some batteries and warranties might also use cycle limit, or a number of discharges/recharges, so the battery and warranty are guaranteed, for example, for 10 years or 6,000 cycles, whichever is first. Lithium-ion batteries generally have a cycle limit of 3,000-10,000 cycles.

This doesn’t mean your battery will drop dead on its tenth birthday, just that you can expect it to have degraded no more than a certain amount by that time.

What Affects a Solar Battery Lifespan?

Your usage, along with other factors are important to solar battery life expectancy. If you are new to storage battery backup, here’s what to keep in mind in the near- and long-term. The better you care for your battery or battery bank in these categories, the more likely you’ll get 10+ years of reliable usage. 

Your battery usage

It’s pretty straightforward. The more you use the battery, the more cycles of discharging and recharging you’ll use.

Lithium-ion batteries can go through a higher number of cycles and deeper discharges than other battery types, but no battery has an infinite cycle limit. 

Battery type

Lithium-ion batteries are the most-used type for pairing with home solar systems as they have high energy density and a longer expected lifespan. Lead-acid batteries use an older technology and have a shorter lifespan than lithium-ion, but might be a lower cost option for battery backup. 

Flow batteries are a promising, new tech. They are still infrequent in use, especially in residential use, as they are expensive and large, but prospective pros include a longer lifespan and being able to discharge to 100% with no harm to battery performance or lifespan.

Protection

Protecting batteries from the elements, temperature changes, and physical damage, will help performance, capacity, and lifespan. You want to install batteries in a stable temperature, not subject to very cold or very hot temperatures. Temperature-controlled spots away from potential damage from weather are best. 

Depth of discharge

Depth of discharge is the degree a battery is emptied before it’s recharged. Charging before a battery is empty, or “shallower” discharges, leads to longer battery life and longer capacity retention.

For the longest likely lifespan, it’s recommended to set your battery management system to a depth of discharge of 50-80% (or leaving a state of charge of 20-50%) as opposed to letting your battery discharge to 20% or less. 

Experts also recommend not charging a battery to 100% charge. Capacity lifespan is shown to be shortened by filling a battery, the state of charge, over 80%. The 20−80% sweet spot is a practical rule-of-thumb.

Can I Extend the Lifespan of My Battery?

There are some simple, routine steps you can take to extend your battery’s life and dependability. A battery’s management system and temperature (thermal) control system should do much of this automatically. Here’s more you can do or check periodically. 

Is a Solar Battery Worth it?

A solar battery gives you greater energy independence and better safety in an outage. In some places, it can increase your energy savings, especially over the long-term. 

It’s more likely to be a good financial decision where your local utility has low net metering or net billing rates so storing and using your excess solar power makes more sense than sending it back to the grid and then using grid power regularly (mostly, each night). Where your time-of-use rates have a large difference between peak and off-peak rates, storing free or less expensive power, and using battery power during high-rate periods may be worth it.

Another way to track your home’s energy usage is with the new Palmetto app. You can see real and potential energy savings for your home and earn discounts in the app’s shop, including $1,000 off a home backup battery. You can also use our Savings Maximizer tool to explore ways to save or get a solar quote for your home.

Frequently Asked Questions

How long can a battery power your home?

This depends on many factors, largely battery size, how much of your home or how many appliances/devices you are powering with battery power, and if you can recharge the battery through an outage with solar panels. A residential solar battery may be able to run essential or emergency power needs for 24 hours or longer, but a whole-home power load for only a few hours, before needing to be recharged.

Will a battery last as long as home solar panels?

Home solar panels are likely to last longer than solar backup batteries. Solar panels are often warrantied for 25 years. Batteries are often warrantied for 10 years. Both can last longer than those estimated lifespans, but you’ll likely need to replace or add to batteries during the lifespan of a solar panel system. 

How long does a Tesla battery last?

A Tesla Powerwall battery has a warranty of 10 years, which guarantees the battery having at least 70% capacity after 10 years.