“Solar batteries wear out too quickly!”, sounds like a reason to second guess installing solar, right? Fortunately, they’re nothing like those AA batteries you throw in your kids’ toys or use for your TV remote. Solar batteries are designed to last much longer, taking several years before they start to show any decline. In this article, we’ll take a closer look at how long a solar battery can last, the factors that affect its longevity, and practical tips on how you can help “extend” its lifespan.
How Long Do Solar Batteries Last?
Modern home solar batteries are built to last between 10 to 15 years, thanks to advancements in lithium-ion technology. In particular, these two battery types: Lithium-ion (or NMC) batteries and lithium iron phosphate (LiFePO4) batteries.
In fact, many battery manufacturers are so confident in their performance that they offer warranties of 10 years or more.
This is a huge upgrade compared to the older, less efficient lead-acid solar batteries which only last 5 to 7 years (and have mostly been phased out).
Considering solar panels have a life expectancy of 30 to 35 years, a solar battery should only need replacing about twice over your panel’s lifespan – a pretty hands-off setup, if you ask us.
Factors That Affect the Lifespan of Solar Batteries
Solar batteries degrade at different rates, and while it might seem like battery type alone (such as lithium-ion versus lead-acid) is the key reason, there’s actually more to it than that.
Depth of Discharge (DoD)
Depth of Discharge (DoD) refers to how much of the battery’s energy you can use before it needs to be recharged. The further you discharge the battery, the more strain it puts on the system, which can lead to quicker wear and tear – and ultimately, a shorter lifespan.
For comparison’s sake, let’s take a look at how lithium-ion batteries fare against the older lead-acid batteries.
Lithium-ion batteries usually have a DoD of around 90%, although, some batteries, take it up a notch higher. For instance, the SolarEdge Battery, one of the more reliable battery brands Avail Solar installs and recommends, boasts a 100% DoD.
Source: SolarEdge Battery Data Sheet
That means you can use the entire capacity (9.7 kWh in this case) without damaging the battery.
On the other hand, lead-acid batteries have a much lower DoD of about 50%. This means you get less usable energy per charge, and they’re more prone to wear and tear over time.
Battery Usage Intensity
Probably the one that makes sense in a snap – If you rely heavily on solar to power your entire home every night, like in off-grid systems, you’re cycling the battery every single day. As a result, your battery will reach its end of life much faster…
Much like how our phones and gadgets don’t hold a charge as well after a couple of years of heavy use.
If you’re using your solar battery just as a backup for power outages or emergencies, you won’t be cycling it as often. This means fewer charges and discharges, which helps extend the battery’s longevity.
Environment
Both extremely cold and hot conditions can take a toll on your solar battery over time. At the heart of it, it’s all about chemistry.
In cold temperatures, the chemical reactions inside the battery slow down. This makes it harder for the battery to charge and release power, and over time, it can reduce the capacity.
On the flip side, excessive heat speeds up wear and tear, making the battery lose its capacity.
“I’ll just put it in the garage then…” Sure, that might work – generally speaking. But here’s the catch:
- A garage without proper insulation can drop to freezing temperatures, affecting the solar battery.
- A garage without good airflow or ventilation can cause temperatures to right too high, potentially leading to overheating.
The good news is that solar battery manufacturers often specify safe temperature ranges in their manuals.
For example, Solar Edge outlines safe temperature ranges and even includes recommendations on where not to place solar batteries in their installation manual.
Source: SolarEdge Battery Installation Guide
So, you should be able to get a clearer idea of the best spots in your home to store your battery and what changes you can make to keep it within those optimal conditions.
Tips to Make Your Home Solar Batteries Last Longer
Yes, solar batteries don’t last forever. But there are some smart moves you can make to utilize the expected lifespan of a battery and ensure you won’t face any significant performance dips or early failures.
- Stick to the Manufacturer’s Depth of Discharge (DoD)
As mentioned earlier, this is the percentage of its charge you can safely use before it needs recharging. Check your battery’s manual to see the recommended levels to keep wear and tear at a minimum.
- Store your battery in a place with stable temperatures.
Aim to store your battery in a place where temperatures are steady, ideally between 50°F and 77°F (10°C to 25°C).
Good options include a well-ventilated garage, basement, or a temperature-controlled shed. If stored outdoors, make sure it’s in a shaded area with proper airflow.
Avoid placing your battery in direct sunlight or near appliances that generate heat.
- Monitor battery health regularly.
If your battery comes with an app or monitoring system, download and set it up. Check the app routinely so you can catch any issues like unusual discharge rates or overheating.
- Use your batteries wisely.
As much as you want to run your entire home on solar power alone, doing so can put a lot of strain on your battery. If possible, try setting limits on usage. You might configure it to only power the essential appliances during the night or when the sun isn’t shining.
- Check your battery’s terminals and cables every few months.
If you notice any dust, dirt, or corrosion, clean them gently to maintain good conductivity. Do not use solvents or any harsh chemicals, as they may be flammable and damaging to the battery.
FAQs on Solar Batteries
What happens to a solar battery’s capacity over time?
Just because a solar battery is rated to last up to 15 years, doesn’t mean it’ll perform with the same efficiency from year 1 all the way to year 15. In reality, solar batteries naturally lose some capacity each year and they’ll hold a little less charge over time.
And that’s because each time your battery charges and discharges, it uses a bit of its “life” – a cycle, as we call it. This cycling slowly reduces how much energy it can hold.
For solar batteries, this capacity loss is gradual, but you might notice a difference around year 5 or so. Around year 10, a solar battery will have lost about 30% of its original capacity, leaving you with 70% working capacity.
How do I know if my solar battery is nearing its lifespan?
You can spot a solar battery nearing its end through a few clear signs:
- Significant reduction in storage capacity. For example, if your battery used to store enough power for your home to last through the night, but now only lasts a few hours.
- Frequent need for recharging, even under similar conditions and energy usage
- Longer charging times
- Sudden shutdowns, especially under heavy load
- Warning from the battery management system, which may indicate that the battery may need to be replaced soon.
- Physical issues, like swelling, leaks, and corrosion, which suggest internal degradation
How many hours does a fully charged solar battery last?
We’ve talked about a solar battery’s lifespan in terms of years, but how long it lasts on a single charge is another matter. How long a fully charged solar battery will last varies, depending on two primary factors:
- Battery capacity
The battery’s capacity, usually measured in kilowatt-hours (kWh), determines how much energy it can hold. For example, a 10 kWh battery can theoretically power 10 kW of devices for one hour or 1 kW for 10 hours.
- Household energy use
Smaller appliances like LED bulbs, refrigerators, routers, and laptops won’t eat up much power. But if you’re also powering energy-hungry devices like microwaves, HVAC systems, or space heaters, your battery will drain much faster. Make sure to examine and calculate your energy consumption to get a better sense of your needs.