Introduction

It’s well-known that because sunlight is only available in the daytime, solar energy cannot be harnessed at night. That is why the energy gets stored in batteries for use at night, or on cloudy days.

Have you found yourself wondering if you can use a car battery for a solar panel? Well, wonder no more, because the answers you’re looking for are right here. We’ve compiled this article to deal with this question, and also to explain the reasons behind the answer.

Can I Use a Car Battery for Solar Panel Energy Storage?

This is a commonly asked question because car batteries are cheap and readily available. You may have an old one sitting in your garage, and we can understand why you might want to use it.

So our immediate answer is yes, you can, but you shouldn’t. It will work, but that’s not the problem. To explain why it’s a bad idea, we need to cover the reasons we don’t recommend it.

But first, let’s look at the reasons why you may be tempted to give it a try.

Reasons You May Want to Use a Car Battery for Solar Panels

There are several reasons why you may have considered using that spare car battery for your solar setup. 

Both Car and Solar Batteries Are Rechargeable 

Batteries used for storing energy from solar panels and car batteries are both recyclable. 

They Share the Same Voltage

Most batteries have a voltage of 12V and therefore there you may think there’s not much difference between the two. The best battery to use for your solar panels is a 12-volt deep cycle solar battery. This one is designed to be used for solar energy. 

Reasons You Should Not Use a Car Battery for Solar Panels

Above, we dealt with the reasons why you may be tempted to use a car battery for your solar panels. But these are the reasons why you really shouldn't do so.

Lead-Acid vs Lithium

The type of battery required for a solar setup is a deep-cycle battery. This means that it’s designed to be regularly discharged, with most of its capacity being used.

Most car batteries are lead-acid batteries, and these are available as deep-cycle batteries. The best batteries for storing solar energy are lithium deep cycle batteries. 

While electric vehicles may use lithium batteries and this makes them a better bet, this is still not the best option.

Deep Cycle vs SLI

A deep cycle battery can be recharged fairly quickly and then used continuously for hours. Car batteries are usually SLI-type batteries, which stands for start, light, and ignite. 

This means they’re designed for providing the short burst of power required to start a car’s engine.

Differing Life Cycles

You have probably heard of the “cycle life” of a battery, but do you really know what it means? When a battery gets discharged and then recharged, it’s known as a cycle. The cycle life refers to the number of times a battery can go through that cycle. 

Unlike solar batteries, car batteries aren’t designed for this type of continuous use. As a result, car batteries have a far lower cycle life than solar batteries.

Why Do You Need a Battery to Store Solar Power?

Even the best solar panel array is limited by its exposure to the light and heat of the sun. The sun isn’t out at night, and on overcast days there won’t be enough solar energy for your solar panels to capture. If it’s not stored, much of the energy that your panels collect will be lost. 

How Your Solar Panels Work to Gain Power

While solar panels do reflect light and some of it can go to waste in this way. Solar panels reflect heat to a degree too, but this isn’t the main issue. Your solar panels get energized by the sun’s rays. Photovoltaic action takes place in the cells of each panel, and this is converted to electricity. 

Although solar panels produce AC and not DC power, this is changed to DC by the inverter to be used throughout the day in your home.  When users wonder about that gentle hum that can be heard sometimes, it’s actually solar panel inverter noise that causes it.

How Your Solar Battery Works to Store Power

When the sun goes down, if that power hasn’t been stored, it will all have been in vain. That’s where a battery comes in. It’s the backup you need for storing that power for use when the sun isn’t available.

So why do solar panels have a peak power rating then? This only indicates the maximum power a solar panel can put out at one time. It’s of no use if you don’t have the right battery for solar energy storage. 

What Will Happen If You Use a Car Battery Instead of a Solar Battery?

If you feel that you have no choice and insist on using a car battery, there’s something you need to know first. 

Depth of Discharge

The depth of discharge is the amount of energy that can be pulled from a battery at a time. The type of battery that’s best for solar energy storage should allow for 80% of its power to be discharged. This is why it’s called a deep cycle battery. 

This type of battery can have a cycle life of up to 5,000 cycles.

Premature Battery Death 

Car batteries aren’t designed for deep discharge. They allow for up to 50% of their capacity to be discharged. If you continuously try to push it beyond that, the car battery won’t last long and will ultimately die.

Why Car Batteries Are Not Deep Discharge

A reason a car battery lasts quite a while even though it has a low cycle life is due to its purpose. A car battery is only required to start the engine. It’s not supposed to be fully discharged. It’s partially discharged to start the engine but then is recharged again by the car’s alternator.

Why Do Batteries Fail?

Every battery is subject to eventual wear. When you use the wrong type of battery, it wears a lot more quickly. There are two main areas of concern when using a lead-acid car battery for solar power. These two issues lead to a dead battery sooner than you’d like.

Lead Plate Erosion

Inside the lead-acid car battery, you will find lead plates, and these aren’t designed to offer prolonged power. These plates shed tiny particles during each cycle. Over time, this can lead to an exposed connection. 

Lead Particle Sludge

Lead sulfate is quite a soft metal. It wears away, and after some time, these particles build up at the bottom of the battery casing. This becomes a sludge, which can interfere with the plates and cause a short. It’s the leading cause of battery death in lead-acid batteries.

Best Car Battery for Solar Energy

If you simply must use a car battery, use a lithium-ion rechargeable battery that’s used for electric vehicles. This is similar to a solar battery and can be used if necessary. Ordinary lead-acid car batteries are never recommended for use with solar energy.

The Best Solar Battery

You follow the instructions for the best batteries and battery chargers when you buy small appliances, don’t you? Don’t let this be any different. Solar batteries are specifically designed for solar energy conditions. And we have the best selection of solar batteries and chargers for your needs. 

Conclusion 

We hope that armed with this knowledge, you make the sensible decision and only use solar batteries for your solar energy storage. We make it so easy for you to get the best battery and charger for your needs. So make the right choice, and get the right battery.

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