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How To Pick Out The Best Battery For a Solar Panel System, Battery Bank, or Off-Grid System

Have you ever wondered how to pick out the best battery(s) to your solar panel system (or off-grid energy system)? Or have you wondered what makes one deep cycle battery greater than another?  If so, this article will answer these questions and give you specific things to check on before buying your new battery (to make certain you get the most bang for your buck)!

When choosing a battery (or batteries) to your solar panel system, there are 3 categories of batteries which work best.    We’ll do this in two parts:

Part 1)   Instantly compare the three chief types of solar batteries (lead acid, saltwater, and lithium).   And,

Part 2)   Compare the elements of batteries, such as: depth of discharge, capacity and power, efficiency, battery life, and manufacturer.

By the conclusion of this article you will know just how to pick the ideal battery to your own solar panel system!

So let’s get started…

So the first decision to make is the type of battery that will fit your system.

Lead Acid Batteries

Lead acid batteries are the most commonly used rechargeable battery in the world. They are also one of the longest-used and most reliable batteries in existence.  Compared to the other batteries we’ll discuss in this report; they’re the cheapest option but you trade price for some battery life and depth of discharge.  But for homeowners needing lots of storage for a lower price, or whether you are simply making the move to a solar panel system, lead acid batteries may be a very good option.  They’re the type of battery we use in most of the battery banks within our solar panel systems.

Saltwater batteries are more expensive than lead acid batteries, but also have a greater lifespan.  Unlike lead acid batteries, saltwater batteries are essentially brand new to the industry and stay both somewhat untested and harder to come across.  Of the three kinds of batteries, saltwater has the best depth of discharge, so you’ll get the most output per charge before needing to recharge.

Lithium Batteries

Lithium batteries are the most expensive and the longest lasting of the three kinds of solar batteries.  Their depth of discharge is less than that of a saltwater battery, but more than that of a lead acid battery. Comparing all three choices, the lithium battery may be the highest rated, but also the most expensive.  An example of a lithium ion battery is the Tesla Powerwall.

Part 2) Compare the elements of batteries.  Once you’ve chosen the best battery type for your own solar panel or off-grid system (that meets your system’s needs), there are components to research to find the ideal battery for your system.  

Cost

Cost is probably one of the more obvious elements.  But the old saying,”you get what you pay for” holds true when buying batteries as well.  In some instances though, certain batteries could be overkill for your system so the most expensive battery might not be the best choice always.

For many systems, a battery will cycle daily, meaning it is going to drain and charge regularly.  With each cycle, the battery’s ability to hold the same charge lessens slightly.  So one component to consider is the warranty on the battery which guarantees a specific number of cycles of useful life.  But keep in mind that if you use the maintenance and reconditioning methods we teach you in the EZ Battery Reconditioning program, you can extend the life of your batteries.

Depth of Discharge

Depth of discharge is how much you can drain the battery down before needing to recharge the battery without damaging its life.  Particular solar batteries may be depleted farther than others, allowing for more use between charging.  Basically, a battery with a 90% depth of discharge per cycle will provide more battery power per charge compared to a battery with less.

Capacity and Power

Measured in kilowatt hours (kWh), capacity is the amount of energy a battery can store over time. The more capacity a battery has, the more power it can store.   Power is how much energy that a battery can provide at a certain moment.  A battery with both a high capacity and higher power can run a massive system for several hours; a battery with low capacity and high power can operate a large system but just for a brief time.

Efficiency

Efficiency is the amount of energy used compared to the quantity of energy it took to store said energy.  Batteries require power to charge and efficiency compares the energy taken to control a battery together with the amount of energy that the charged battery produces.  The higher the efficiency, the more cost-effective the battery.

Manufacturer

This might not be a component most would consider, but it’s something to focus on.  Like other technology, there are both reputable brands and start-up brands.  A trusted brand comes with known defects and benefits; a startup brand can perhaps have better technology, but could also have unknown technological difficulties.  Depending upon your system needs, you may decide to go with a well-reviewed firm or one that is brand new to the market.