To obtain the maximum performance and lifespan from your batteries, it's helpful to learn everything you can about solar batteries to assist you in making the best purchase possible.

Today's solar batteries are available in modern, high performance, and long-lasting designs, such as lithium ion. The latest state-of-the-art ones require little to no upkeep and may easily last the lifespan of your solar panels.

To achieve the maximum performance possible from your solar PV system, it's essential to know just what to be on the lookout while on the hunt for your new batteries. This reference guide will provide you with a brief rundown of the most commonly used types of  batteries available, including tips that you can use to extend their lifespan.

Other factors to take into consideration that potentially affect the lifespan and performance of your batteries include the manufacturer that you choose, the warranty included with your purchase, and following certain industry practices to maintain the lifespan of your batteries.

We'll review the pros and cons of the principal solar battery types including:

battery icon

Image via Flaticon

  • Flooded lead-acid batteries
  • AGM batteries
  • Lithium ion phosphate batteries
  • Gel batteries

Read on to learn more about solar battery options and discover the tips for longer-lasting solar batteries and performance!

Solar Batteries

Flooded Lead Acid Batteries

Flooded lead batteries were once the standby batteries for use in solar panels, and the only solar batteries available.

Flooded lead batteries have a safe, proven and efficient track record. They are the most cost-effective option available upfront, although newer alternatives work out to be more profitable in the long run with a higher initial investment.

If you dedicate much of your free time to the maintenance and upkeep of your solar PV system, flooded lead batteries may be the right option for you.These batteries require maintenance and careful monitoring but can be a highly rewarding and energy efficient purchase.

AGM Solar Batteries

AGM, or absorbent glass mat batteries, are a modern and updated option over flooded lead-acid batteries that require little maintenance or upkeep. If you prefer to perform only brief maintenance on your solar PV system, AGM batteries are the ideal choice.

AGM batteries are a type of flooded lead battery that gained popularity during the 1980s as a lightweight alternative to traditional flooded lead. Fundamentally speaking, an AGM battery is a sealed flooded lead-acid battery.

AGM batteries produce lower internal resistance over traditionally flooded lead batteries, meaning that they are resistant to cold temperatures and leakage. AGM batteries are a longer lasting option because they self-discharge more slowly than traditional flooded lead batteries.

This slower self-discharge is also a result of their decreased internal resistance. AGM batteries don't require the level of ventilation that flooded lead-acid batteries need, and because of their captive electrolyte, are virtually leakproof.

The lower internal resistance produced by AGM batteries when compared to flood lead-acid batteries means that AGM is not prone to overheat, is nonhazardous, and is resistant to cold. AGM batteries can also hold a static charge for a more extended period.

With all of these improvements when compared to traditional flooded lead-acid batteries, AGM is only slightly more expensive. These factors make AGM batteries a favorite choice for powering off the grid solar PV systems.

Universal Power Group 12V 100Ah Solar Wind AGM SLA DEEP Cycle VRLA...
  • UPG #45978 UB121000 12V 100Ah
  • Dimensions: 12.17 inches x 6.61 inches x 9.16 inches. Weight: 63.93 Lbs
  • SLA/AGM maintenance free, spill proof battery

Gel Batteries

Gel batteries are a ventless, low maintenance option that shares many characteristics with AGM batteries. Gel batteries stand up to extreme temperatures and are resistant to vibration and shock. Although they discharge more quickly than AGM batteries, their long-term lifecycle is longer.

Unfortunately, gel batteries are easy to damage by overcharging and are prone to other malfunctions related to their low charging profile. Gel batteries are more costly than AGM batteries, making AGM a more desirable choice for many solar PV system owners.

If properly charged with the use of a solar controller, gel batteries prove to be a long-lasting option that is best suited to extreme environments and can outperform both AGM and flooded lead batteries in overall performance.

Mighty Max Battery 12V 100AH Battery for Solar Wind DEEP Cycle VRLA...
  • ML100-12 SLA is a 12V 100AH group 30H Sealed Lead Acid (SLA) rechargeable maintenance free battery
  • Dimensions: 12.17 inches x 6.61 inches x 8.30 inches. Listing is for the Battery and Screws only. No wire harness or...
  • Factory activated SLA / AGM battery. Maintenance free. No adding water. Advanced design works right out of the box and...

Lithium Ion Phosphate Solar Batteries

Lithium-ion batteries are the latest and generally speaking, most expensive solar battery option. The benefits associated with a lithium-ion battery for solar PV systems are numerous, and the cost of these highly efficient alternatives to AGM is steadily decreasing.

When it comes to putting tips for longer lasting  batteries into action, opting for lithium-ion phosphate is often your first step. Lithium-ion phosphate batteries for solar PV systems are safe, lightweight, and offer the greatest lifespan available on the market.

Unlike AGM or flooded lead, lithium Ion phosphate batteries require no maintenance for 15-20 years.

Advancements in lithium-ion technology allow for these batteries to maintain the ultra low resistance that produces the numerous advantages associated with lithium-ion phosphate, including high thermal stability and superior electromechanical performance.

In comparison to AGM or gel batteries, lithium ion offers an equally efficient discharge rate and overall lifecycle, the highest rated performance available in both categories. If your solar PV system doesn't require much upkeep, you won't have to worry about leaving lithium ion phosphate batteries idle–they won't discharge or lose power like older forms of solar batteries.

Generally speaking, the only disadvantage to choosing lithium-ion batteries for your solar PV system is an increase in cost over long-standing options like AGM. In the long run, lithium ion compensates for its higher price tag by outlasting gel, AGM, and flooded lead-acid batteries.

Tips to Make Your Solar Batteries Last

Once you've selected the best option for your solar PV system, preferably lithium ion phosphate batteries, small tips, and tricks to extend the life cycle of your batteries will help you achieve maximum use of your solar energy system. Follow these tips for longer-lasting batteries

Limit the Number of Batteries in Use at One Time

When it comes to solar energy, more batteries doesn't equal more power. Overloading your bank is one sure way to overload your batteries and potentially shorten their lifespan. This loss of power is the result of increased resistance when too many batteries are in use. Internal resistance is the enemy of batteries and their lifespan.

Rotate Your Batteries Occasionally

Rotating batteries will ensure that all of the batteries inside of your bank receive an equal charge. Often, batteries placed near the middle of the bank receive less charge than batteries placed at either side. Rotating batteries will refresh and equalize their charge.

Use a Large Battery Interconnect Cable to Reduce Resistance

Once again, internal resistance is the enemy of your battery's lifespan, and you should take steps to decrease it whenever possible, thus increasing battery life and performance.

The cable that you select should be sized accordingly to your voltage system. Choose a 4/0 cable for 12V or 24V solar PV systems and a 2/0 cable for 48V systems.

Avoid Leaving Solar Batteries Uncharged or Idle

Along with internal resistance, idleness is an enemy to your battery's lifespan. Although lithium-ion phosphate batteries can most effectively function without a charge or when left idle, it's never a good idea to intentionally leave any batteries idle or without a charge for extended periods of time.

Over time, uncharged batteries are prone to a damaged lifecycle and charging profile.


Image via Pixabay

Consider Purchasing a Battery Desulfator

Battery desulfators may extend the lifespan of batteries by eliminating excess sulfate. Although the effectiveness of desulfators varies, they may be a critical step in maintaining the lifespan of your batteries.

Consider Equalization

While uncontrolled overcharging of  batteries should be avoided and can result in damage and decreased lifespan, properly equalizing your batteries using the method outlined in your manufacturer's instruction manual may extend their lifespan and improve performance.

Consult your manufacturer's instruction manual for exact instruction on performing equalization. You must follow these instructions exactly and take any necessary safety precautions.

Mighty Max Battery ML35-12 - 12V 35AH DC DEEP Cycle SLA Solar Energy...
  • ML35-12 SLA is a 12V 35AH Sealed Lead Acid (SLA) rechargeable maintenance free battery.
  • Dimensions: 7.68 inches x 5.16 inches x 7.13 inches. Listing is for the Battery and Screws only. No wire harness or...
  • SLA / AGM spill proof battery has a characteristic of high discharge rate, wide operating temperatures, long service...

Final Thoughts: Further Considerations to Get The Most Out of Your Solar Batteries' Lifespan

Now that we've covered the most common types of solar batteries available, reviewed their advantages and drawbacks and have provided you with a quick tip list, there are a few more in-depth factors you may want to consider when purchasing your solar batteries to obtain the longest lifespan possible.

Familiarizing yourself with these terms and practices will extend the life of your solar batteries even further.

Depth of Discharge

The depth of discharge, typically abbreviated as DoD, refers to the amount of a battery's capacity that has been used. By never allowing your batteries' DoD to fall below this threshold, you will extend their performance and lifespan.

An average Depth of Discharge is around 90 percent. This figure means that to maintain the lifespan of your solar battery, you should avoid letting your charge fall below the 90% remaining power mark before reconnecting to a power source.

Choose Your Manufacturer and Warranty Wisely

When shopping for solar batteries, take factors like the manufacturer and warranty plan you choose into consideration. Often, manufacturers will include a warranty with your purchase that may cover any malfunction of or replace a battery that has worn down before it's guaranteed lifespan.

The manufacturer you choose when shopping for batteries also impacts the quality of your purchase. Consult online review sources for information about the brand you select and comb reviews for information regarding battery lifespan.

Just a little buyer research beforehand will go a long way in ensuring that your new solar batteries achieve their highest possible lifespan and performance.

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