Lithium Batteries vs. AGM Batteries: Which is the Best Solar Backup Battery for Home

Whether you have the solar panels on your rooftop or is going to plan to get off the grid, you need one or several batteries. Why? Because solar batteries can store energy, providing you an independent energy solution to powering your home or your RVs. When you start to pick up one for your home backup battery, you may come across two common types of solar batteries, AGM and lithium battery. What is better?

In this post, I will answer this question to help you make an informed decision and choose the best type of solar battery for your needs.

What is an AGM(Absorbed Glass Mat) Battery?

AGM battery is a type of lead-acid battery that uses a fiberglass mat to absorb the electrolyte and keep it in contact with the plates. It has a higher capacity, efficiency, and durability than gel cell batteries, and it can handle high currents and deep discharges. It is spill-proof, maintenance-free, and less sensitive to temperature changes. However, it is also more expensive, heavier, and more susceptible to overcharging and damage from heat.

Relate: AGM Deep Cycle Battery Guide

What is a Lithium Battery?

A lithium battery is a type of battery that uses lithium metal or lithium compounds as the anode, the negative electrode. Lithium batteries have a high energy density, meaning they can store a lot of energy in a small volume and weight. Rechargeable lithium batteries are frequently used for home energy storage.

SVC Solar Lithium Battery for Home Energy Solution

solar high voltage lithium battery for solar
solar backup battery for Home
solar backup battery for Home

Relevant Reading: Best Lithium Batteries for Off-grid Solar

There are the common types of lithium battery

Lithium-metal battery: This is the simplest type of lithium battery, which uses pure lithium metal as the anode and a variety of materials as the cathode, such as manganese dioxide, carbon monofluoride, or thionyl chloride. It has a high energy density, but it is also unstable, expensive, and prone to short circuits and thermal runaway.

Lithium-ion battery: This is the most popular type of lithium battery, which uses lithium ions as the charge carriers between the anode and the cathode. The anode is usually made of graphite or other carbon materials, while the cathode is usually made of metal oxides, such as lithium cobalt oxide, lithium iron phosphate, or lithium nickel manganese cobalt oxide. It has a high power output, efficiency, and cycle life, but it also requires a sophisticated battery management system to prevent overheating, overcharging, or over-discharging.

Lithium-polymer battery: This is a type of lithium-ion battery that uses a polymer electrolyte instead of a liquid electrolyte. The polymer electrolyte can be either solid or gel-like, and it allows the battery to have a flexible, thin, and lightweight shape.

Differences between AGM and Lithium Batteries

Size and Weight

Lithium batteries primarily stand out for their smaller size and lighter weight compared to AGM batteries and all other lead acid batteries for that matter. This makes them ideal for space-constrained applications or situations where weight is a critical concern. Lithium batteries weighing approximately one-third to one half of AGM batteries on average.

Energy Density

Energy density is a key determinant of battery performance. Lithium batteries offer a greatly higher energy density than AGM batteries, which means a lithium battery can store more energy in the same size and weight as an AGM battery.

Depth of Discharge and Cycle Life

Depth of discharge (DOD) refers to the amount of energy that can be discharged from a battery without causing long-term damage, while cycle life is the number of charge-discharge cycles a battery can undergo before its capacity is significantly reduced.

Compared to an AGM battery, an lithium battery has a higher DOD and longer lifespan.

Normally, it is generally recommended to discharge the AGM battery to approximately 50% – 60% of their capacity to maximize their cycle life,while lithium batteries can be discharged more deeply without causing long term damage.


AGM batteries have a shorter lifespan, typically between 2 and 5 years, while lithium batteries can last between 5 and 10+ years.


AMG batteries cost less than lithium batteries. However for the long term, the lithium battery provide more beneficial return with the longer lifespan and higher energy density.

When choosing the solar backup battery for home, it’s essential to weigh the short-term expense against the long-term benefits.

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