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

Or have you wondered what makes one deep cycle battery greater than another?  If so, this report will answer these questions and provide you specific things to check on before purchasing your new battery (to ensure you get the most bang for the buck)!

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

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

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

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

So let’s begin…

There are three battery types that work exceptionally well; however, each battery type has pros and cons. So the first decision to make is the type of battery that will fit your system.

Lead acid batteries are the most commonly used rechargeable battery in the world. They’re also among the longest-used and most dependable batteries in existence.  Compared to the other batteries we will discuss in this report; they are the cheapest option but you trade cost for some battery life and depth of discharge.  But for homeowners needing lots of storage for a lower cost, or whether you are simply making the transfer to a solar panel system, lead acid batteries might be an excellent option.  They’re the type of battery we use in the majority of the battery banks in our solar panel systems.

Saltwater batteries are more expensive than lead acid batteries, but also have a better lifespan.  Contrary to lead acid batteries, saltwater batteries are basically brand new to the market and stay both somewhat untested and more difficult to come across.  Of the 3 types of batteries, saltwater has the best depth of discharge, which means 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 options, the lithium battery is probably the highest rated, but also the most expensive.  A good example of a lithium ion battery is the Tesla Powerwall.

Part 2) Assess the components of batteries.  As soon as you’ve chosen the best battery type for your own solar panel or off-grid system (that meets your system’s needs), there are elements to research to find the perfect 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 purchasing batteries as well.  In some instances though, certain batteries may be overkill for your system so the most expensive battery might not be the best choice always.

Battery Life and Warranty

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 maintain the identical charge lessens slightly.  So 1 component to consider is the warranty on the battery which guarantees a certain number of cycles of useful life.  But bear in mind that when you use the maintenance and reconditioning methods we teach you in the EZ Battery Reconditioning application, you can extend the life of your batteries.

Length of Discharge

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

Ability 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 save.   Power is how much energy that a battery can provide at a given moment.  A battery with both a high capacity and higher power can run a large system for many hours; a battery with low capacity and higher power can run a large system but only for a short time.

Efficiency

Efficiency is the amount of energy used compared to the amount of energy it took to store said energy.  Batteries require power to control and efficacy compares the energy taken to charge a battery with the amount of energy which the charged battery produces. 

Manufacturer

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