AGM or Lithium Ion: Which type of battery is suitable for residential solar?

Off-grid photovoltaic solar panel systems include photovoltaic panels, charge controller and solar batteries – deep discharge batteries. These solar inverter batteries (deep discharge batteries) are a key component in a renewable energy system. The batteries needed to store the energy produced by a wind installation, a solar panel or a hydro electrical system, which will be connected to the utility network, are of the solar batteries type, if you want to use electricity independently of the network or in case of a power failure.

Unlike other types of batteries, solar batteries are designed to be discharged and recharged repeatedly. In order to keep solar batteries in good working order and to prolong their life, established manufacturers recommend limiting the discharge depth to about 20%. Do not allow the type of solar batteries to be discharged more than 50% discharge depth. Sometimes an inverter has the role of disconnecting consumers to protect solar batteries. Monitoring solar batteries helps to better maintain them and provides statistics on the general health of solar batteries.

Solar battery size varies

Solar inverter batteries can be small or very large. In general, the size and weight correspond to the capacity of the solar batteries (ampere-hours of storage). The type of solar batteries includes many sizes: from solar inverter batteries that weigh less than 4 kilograms, to solar batteries that weigh over 100 kilograms. If you need a large storage capacity, you need to make sure that you have enough space to store one solar battery or many solar batteries, as needed.

A battery can help or ruin a photovoltaic application. Given the multitude of information we have access to, many people have questions and concerns when it comes to choosing batteries for their photovoltaic system. This begs the question: which is the best option, an AGM battery or a lithium battery?

Both types of solar inverter batteries have both advantages.

First of all, a short definition for each of them:

AGM: The abbreviation comes from “absorbed glass mat” or “absorbent glass mat” and is the most common type of sealed lead acid battery (or SLA for short). The basic idea is to use a glass “fabric” between the plates of the battery that absorbs the acid and which for a slightly higher manufacturing cost than a wet battery It is also less prone to sulfation and has the ability to handle deeper discharge without damaging a “wet” battery. Lower acid gas release as well as longer battery life is two other features that position AGM accumulators above the “wet” batteries. The technology was developed in the 1980s and generally accepted as very efficient in many applications.

Lithium: (in this case) usually means LiFePO4, which is lithium iron phosphate or lithium ferrophosphate – commonly used for photovoltaic batteries and the like (and not Lithium Polymer – used for electric cars and airplanes, or lithium-nickel cobalt aluminum – both used in electric cars (large).

AGM or Lithium? What is the best option?

In picking the sort of solar inverter battery for off grid energy systems we believe that we are currently at an obvious junction. We are at the transition point between lead-acid batteries, technology tried & used for decades and the promise of higher density lithium-ion batteries, improved endurance and a longer life cycle.

But what do we do with lead-acid batteries (AGM)? These equipments have been used for so long that they have become a standard, a normality. Their quality varies significantly depending on the manufacturer, but the technological differences are minimal. AGM batteries have been used for decades, so the natural question that arises is, why would we change this two-century-old technology? That’s why Lithium Ion Batteries are the best option for your residential solar.

Is an AGM battery worth the extra money?

An AGM battery is worth the extra money because it can withstand vibration better than a wet cell lead acid battery.

AGM batteries are made with cells that are individually sealed into containers which then have an oily or gelled electrolyte rather than the sulphuric acid electrolyte of standard wet cell batteries. The separator between each cell also contains less water, meaning these batteries self-discharge much more slowly; they stop generating power when 80% discharged, versus 50% for traditional batteries (depending on the type). The lack of water in both the individual cells and between them means there is no risk of corrosion. Dry charge capability also removes any need to trickle charge before installation.