How Long Do Solar Batteries Last (+ Keep Longer -)

While home PV systems in the US continue to grow, surprisingly few installations have the added storage capacity – only about 8% of home solar power installations in 2020 have batteries attached.

A typical solar battery would last around 5-15 years, depending on the type of battery, usage, recharging, temperature, and maintenance. Considering that a home PV system could have a lifespan of around 30 years, you would need a battery change in its lifetime.

This discussion will investigate the key factors contributing to a solar battery’s life.

  • What types of solar batteries are there
  • What causes a battery to deteriorate
  • How temperature affects the solar battery
  • How to store your solar battery safely
  • Maintenance of your solar battery

Read on and learn how to get the most out of your solar battery.

Old Batteries Rusting In A Warehouse. - Sol Voltaics: Solar Panel Information
Old Batteries Rusting In A Warehouse.

What Are The Different Types Of Solar Batteries?

Three types of solar batteries are available, the lead-acid battery, the lithium-ion battery, and the saltwater battery.

1. The Lead-Acid Battery

Lead-acid batteries are one of the cheapest available on the market. They have been used extensively in off-grid systems for decades until the introduction of the lithium-ion battery; lead acid was the most popular.

The drawback of lead-acid batteries is that they have a much shorter lifespan than lithium-ion batteries because they have a lower Depth Of Discharge (DoD) rate.

The depth of discharge rate is the percentage of battery depletion during a usage cycle—the greater the depth per cycle, the shorter the battery life.

2. The Lithium-Ion Battery

Since the introduction of lithium-ion batteries and the marketing of these products in the USA by companies like LG and Tesla, lithium-ion batteries are the current gold standard for home power storage.

The demand for these products has seen their prices drop by around 85%, and their DoD rates are much higher than those of lead-acid batteries. They, therefore, have a longer lifespan and are more compact and lighter than lead-acid batteries.

These days most storage batteries are lithium-ion as they are affordable, reliable, and robust.

3. The Salt Water Battery

Using saltwater electrolytes rather than the heavy metals of lithium-ion and lead-acid batteries, saltwater batteries are much more environmentally friendly than the others and can be easily recycled.

Saltwater batteries have zero fire risk. While this technology is mainly untested, they don’t hold as much charge or energy density in the same size battery as a lithium-ion battery.

While more research and testing with saltwater batteries are being conducted to make them more efficient, lithium-ion remains the optimum choice for attached batteries on home PV systems.

For solar batteries that have the most extended lifetime and the most number of cycles, and are the safest, then the lithium-ion phosphate (LFP) batteries are best.

For the best compact solar batteries (where space is a concern) that deliver the most storage, lithium-ion nickel manganese cobalt (NMC) batteries would be the best choice.

Single 100Ah Lithium Ion Battery - Sol Voltaics: Solar Panel Information
Single 100Ah Lithium Ion Battery

What Causes A Battery To Deteriorate?

A few factors influence the lifespan of a solar battery, and the Depth Of Discharge rate is only one of them.

The two main factors are trickle charge and overcharge.

Overcharging A Battery

Overcharging a battery is where the current is driven to a battery that is already fully charged, and this can cause the battery to overheat or even catch fire.

This is one of the reasons why where you store your batteries is essential so that should a fire occur, it would not pose a severe risk to the home itself.

Where batteries are stored around potentially combustible materials, any damage through overcharge could be catastrophic.

Trickle Charging

Trickle charging may seem innocuous, but not allowing a battery to discharge to its threshold and recharge will cause losses over time, and the battery capacity will degenerate.

A battery trickle-charged to 100% and then discharged to just under 100% can overheat, diminishing its lifespan and capacity.

Loss Of Lithium Ions

Over time, side reactions in the battery can capture free or mobile lithium ions, gradually decreasing the battery’s capacity and efficiency as the availability of free usable lithium decreases.

Powerful Rechargeable Battery Forklift. On The Surface Of The Battery Is An Electrical Connector. - Sol Voltaics: Solar Panel Information
Powerful Rechargeable Battery Forklift. On The Surface Of The Battery Is An Electrical Connector.

How Temperature Affects Battery Life

At constant high temperatures, the chemical processes that allow lithium ions to be accepted into the electrode become less efficient as the electrolyte between the electrodes deteriorates and breaks down at elevated temperatures.

The battery may cease functioning at very low temperatures, but low temperatures do not affect the battery’s lifespan.

When looking for the right place to install your battery, you need to consider the effect of temperature. So if you live in a warm to hot climate, an indoor installation (like a garage or shed) may be ideal if neither gets too hot during peak sun hours.

The same would apply if you live in a very harsh winter climate, and storing your battery outside would not be an option in either extreme.

12 Volt Battery White Background
12 Volt Battery White Background

How To Store Your Solar Battery Safely

From the discussion above, where you store your solar battery plays a critical role in its lifespan, and a considerable safety aspect is involved as well. When looking at where to keep your battery, look at the following :

  • Well-ventilated areas meet the manufacturer’s temperature thresholds to extend and maintain battery life.
  • Good spacing between the battery and other components and surfaces allows for good heat dissipation without fire risk.
  • No combustible materials around your batteries to reduce the risk of severe fire or explosion.

Solar Battery Maintenance

To keep your batteries and system in good order, make sure you check the following or have a professional come in and do it for you :

  • Ensure you are not fully discharging your battery daily, which will shorten your lifespan and capacity. If you are, it may be time to increase the battery bank.
  • Check for leaks, fluid, or build-up outside the battery and that the necessary fluid levels are correct.
  • Keep batteries in series at the same charge levels, as varying charges between batteries can adversely affect performance and longevity.
  • Ensure the voltage points for charge controllers and chargers as set by the manufacturer’s specs.

It is far cheaper and easier to maintain a battery properly over time, and while you may not need to check the battery every month, doing maintenance checks on your system should occur at least twice a year.

Best Selling Solar Batteries +

SALEBestseller No. 1
Renogy Deep Cycle AGM Battery 12 Volt 100Ah, 3% Self-Discharge Rate, 2000A Max Discharge Current,…
  • 【Maintenance Free & Safe to Use】Manufactured with thick absorbent glass mat (AGM) separators and advanced valve regulated…
  • 【Outstanding Discharge Performance】Proprietary quinary alloy plates and exclusively treated plate grids enable low…
  • 【Longer Shelf Life】Made of high purity materials, Renogy Deep Cycle AGM Batteries reduce the monthly self-discharge rate…
SALEBestseller No. 2
Trail Camera Solar Panel, WingHome Solar Battery Charger Kit 12V/1A 6V/1.5A with Build-in 2000mAH…
  • 【Universal Compatibility】Compatible with WingHome trail cameras and other brands outdoor security cameras powered by 6V…
  • 【Consistent Free Power】Use sunlight as a source of energy and generate clean & emission free electricity to keep your…
  • 【Easy on the Wallet】No longer waste a ton of money on batteries for trail cameras and other outdoor accessories
SALEBestseller No. 3
OYMSAE 20W 12V Solar Panel Car Battery Charger Portable Waterproof Power Trickle Battery Charger &…
  • ☀[Charge Visualization]The indicator lights can help you understand the charging status: the blue light is on (put in the…
  • ☀[Intelligent Protection] Built-in charging microprocessor, improved charging algorithm, can provide overvoltage…
  • ☀[Higher Conversion Rate]The regular convex points of surface distribution are conducive to the secondary propagation of…

Besides your batteries, you should also ensure your panels are clean and free from dust, debris, and bird droppings. These can also affect the panels’ efficiency by slowly reducing the amount of electricity they can generate and affecting the charging capacity of your system.

Resources

Solar Panel Batteries FAQ

What type of battery is best for solar panels?

There are three main types of batteries used in solar systems:
1. AGM lead-acid batteries
2. Gel lead-acid batteries
3. Lithium-ion batteries

While they are far more expensive than lead-acid battery types, lithium-ion batteries are the longest-lasting, lightest, and most efficient choice for solar applications. 

How long do solar panel batteries last?

In general, most solar batteries on the market today will last between 5-15 years, with lead-acid varieties on the low end and lithium-ion batteries on the high end. Of course, your batteries will need to be properly looked after and maintained to give them the longest possible lifespan. 

What is the cost of solar panel batteries?

The cost of solar batteries depends on the type you choose for your system, but you can expect to pay roughly $400 per kWh on the low end, and $750 per kWh on the high end. Lithium-ion batteries are by far the most expensive but have more than double the life expectancy of other battery types. 

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