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Can I Use Car Battery for Solar Panel? Learn About Batteries and Solars


Solar panels work in daylight and produce the required electricity to run an electric system. First, however, you have to have a battery installed in the panels to store the energy when the sun goes low. For that, this post will answer your question, “can I use car battery for solar panel”?

A straightforward answer would be, Yes. You can use a car battery to store solar energy for future use. However, a car battery is not a suitable option for that purpose.

Therefore, we’ll discuss how the solar panels work and what type of battery you would need for that purpose.

Car Batteries and Solar Panels

You already know that the main purpose of a car battery is to power up the car’s engine. Commonly, a 12V lead-acid battery is used in cars. This battery gives a charge booster for a temporary period, specifically for the car ignition.


When you turn the ignition by a car key, the battery executes the electrochemical reaction and signals to all other electrical accessories, including the engine.

However, a car battery cannot store the electrical charges for longer. It’s the alternator that recharges the battery of your car.

So, it’s obvious that a lead-acid car battery is not the best option for your solar panel system.

What Batteries Should You Use for Solar Panels?

A solar panel uses deep cycle batteries to store the charge. Since solar panels can only work when there is sunlight, they have to store energy when it gets dark.

A lead-acid battery doesn’t hold a charge for longer as compared with a deep cycle battery. Therefore, your solar panel system will keep providing electricity to your house when you install a set of deep cycle batteries with it.

Difference Between Car Battery vs. Solar Battery

A lead-acid or car battery and a solar or deep cycle battery might look similar. You will see no difference in their external battery covers and terminal connections. Even both batteries work on the same principle.

Car Battery

There is an acidic combination in liquid form inside the batteries. This fluid makes sure the flow of current. You will find the electrolytes plates to store the charge. The size and quality of an electrolyte plate also determine the drainage.

Moreover, the negative and positive battery terminals are also there to transfer the electrical charge.

However, the internal structure and working of both batteries differ from each other.


A lead-acid battery uses thin electrolyte plates to transfer the electrical charge. These thin plates can’t hold the charge for long because of their low capacity. However, when you start a motor, typically a car engine, almost 60% of the energy is utilized by the engine alone.

After that, your car’s alternator begins to recharge your car battery. The recharging process depends on the engine’s movement, known as RPM (Revolution Per Minute).

Now, the solar panel system or deep cycle batteries use thick electrolyte plates to hold the electrical energy. The thickness of the plates determines the charge storing capacity (measuring unit: Farad).

You might have experienced the silence in electric cars. That’s because of the deep cycle batteries.

Energy Storage

Lead-acid batteries store a low electrical charge for a shorter period, while deep cycle batteries can hold a high charge for a longer duration.

That’s the reason why your car battery needs recharging after starting up the engine.

On the other hand, the solar battery can store energy depending on the quality of the electrolyte.

The size and quality of the electrolyte determine the storage and drainage. Since the car batteries need to give your car engine a quick burst of energy, the thin plates can quickly discharge and power up your car.

The deep cycle solar batteries have thicker electrolyte plates that will give moderate energy consistently. That’s why you get power in your house even when the sun has set.

Check out the Solar Charge Controller with an LCD display.

Surface Area

The lead-acid or car battery has a larger surface area as compared to a deep cycle battery. Why?

The surface area of a battery helps store charge quickly.

Now, your engine requires 60% of the car battery’s energy in almost 2-3 seconds to kick start the engine. The large surface area helps the car battery create a big electric charge in comparatively less time.

However, deep cycle batteries don’t need to have a large surface area. It’s because these batteries don’t need to start an engine but to consistently transfer energy to a residential or commercial area.


A car battery gets its recharge from either the alternator or a car battery charger and maintainer. Moreover, the alternator keeps recharging the car battery when you drive your car.

When you are not driving your car, you can connect the charger to your car battery and set the amperage and time.

The deep cycle batteries also need recharging. You can connect the batteries to the external charger or a power source. Other than this, you can also allow the solar panels to keep recharging the deep cycle batteries. This function varies from system to system.

Battery TypeWorkingEnergy StorageSurface AreaRecharge
Lead-Acid Car BatteryUses thin electrolyte plates to give a burst of charge. Typically used to start car engines.Has low charge storage capacity because of thin electrolyte plates.Has large surface area to quickly store and release large electric chargeThrough the alternator or an external car battery charger
Deep Cycle Solar BatteryUses thick electrolyte plates to consistently give energy to a house.Has high charge capacity because of thick electrolyte plates.Has comparatively smaller surface area to gradually release moderate electric chargeThrough an external power source or by solar panel system

Similarities Between Car Battery and Solar Panel Battery

No doubt, a car battery and a solar panel battery have things in common. There’s nothing surprising in that because the main purpose of both batteries is to store and transfer electric charge to the attached device.


So, let’s talk about what’s common between the two batteries.


You already know that usually, people use a 12V car battery. That’s the common voltage setting by car battery manufacturers. If you also have a 4-6-cylinder car, the battery inside your vehicle is 12V.

Now, a deep cycle battery also has a 12V voltage setting. Moreover, you can add more 12V batteries in series to increase the voltage when necessary. That will boost the input voltage from 24V to 48V.


The batteries you use in your car and in your solar panel system are rechargeable. Although each battery uses a different recharging method, you can ultimately recharge them.

That’s why you can use

  • Lead Acid Battery
  • Lithium Battery

These types of batteries are commonly used in cars and solar panels.

The common factor in these batteries is that you can recharge them at the end of that day.

Moreover, you can find them for engine starting and renewable energy generation.

These two similarities are most common in a car and solar panel batteries.

What Solar Battery Should I Buy?

Since you have understood the differences, you can easily find a deep cycle battery for your solar panel system.

Solar Panel Battery

According to expert recommendations, an EV battery (Electric Vehicle) fully equipped with lithium-ion is the most suitable option for your solar panel.

Besides, most electric cars use heavy lithium-ion batteries because they are

  • Eco-friendly
  • Sound Proof
  • Lightweight
  • More Charge Cycles
  • Low Maintenance
  • Low Self-Discharge Rate

One of the most important factors in a lithium-ion battery is the charge cycles and discharge rate.

Have a look at the Neptune Gel Deep Cycle Battery for your solar panels.

Charge Cycles

When a battery is completely discharged and recharged again, it counts as one charge cycle. Now it’s not necessary that a battery is discharged in one run. You may stop using the battery and connect it to the charger. But one cycle will only get completed when it discharges completely.

Moreover, the charge cycle for a lithium-ion battery is 8 hours and then 1 hour of use. That means you can use it continuously without facing a cooldown period.

Self-Discharge Rate

This term refers to when a battery permanently discharges on its own. You can’t control the self-discharge rate of any battery. Moreover, the self-discharge rate varies from battery type to type.

For instance, the self-discharge rate is 1.5-2% per month in lithium batteries.

This factor depends on multiple factors, including severe temperature and recharge status. However, you can slow down the self-discharge rate in lithium-ion batteries by keeping them away from the harshness of the weather. Extreme temperatures affect not only lithium-ion batteries but any car or EV battery.

Also, avoid overcharging the batteries as it will affect their performance and lifespan. You can use a battery charger having a timer that will automatically stop charging once the battery is fully charged.

Final Words

It’s better not to use a car battery to store the charge from your solar panels. No doubt, a lead-acid car battery will apparently work for you. But you will start experiencing poor charge performance and fast discharging of the battery.

Therefore, it’s wise to install EV batteries while deploying a whole new solar panel system in your home and your office. That way, you can easily avoid the cost of underground power lines and generate electricity from solar panels.

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