Close this search box.


What Size Solar Panel to Charge 12V Batteries?

When you are installing a solar panel system in your home or office, you are most likely going to connect it to batteries. This allows you to power your appliances even at night without any issues. But using such batteries is only possible when you have the right sized solar panels which can properly charge your batteries.

And to be more specific, you will need the right sized solar panels for charging your 12V batteries. Today, we are here with a complete guide on what size solar panels you need to charge 12V batteries as well as all of the information related to 12V batteries that are used along with solar panels.

What do you Mean by Deep Cycle Batteries?

Deep Cycle BatteriesIn case you are not familiar with the exact batteries used along with solar panels, they happen to be deep cycle batteries. Even though these batteries look almost the same as the batteries used in cars, they are quite different in terms of their functioning.

Such batteries that get used with solar panels are called deep cycle batteries which are perfect for solar panels. This is due to the reason that they offer sustained energy output even over a long period of time quite easily. And despite what battery manufacturers recommend, you can even discharge these batteries to up to 80% if needed.

Where do you Find Deep Cycle Batteries for Solar Panels?

Since solar panels use specific deep cycle batteries, you may not know where you usually get one. Thankfully, most solar panel manufacturers and suppliers will offer these batteries in most cases. You can either get these batteries separately or as a bundle along with your solar panels.

Apart from the 12V battery size mentioned here, you can also find 24V and 48V deep cycle batteries if you need the same. And since these batteries are highly durable for high efficiency usage, you can easily find a wide range of deep cycle batteries at either a solar panel supplier or a battery supplier.

What Size of Solar Panels are Needed for Charging a 12V Battery?

Even if you have a high performance 12V deep cycle battery, it is going to be useful only if it gets charged properly. And to ensure the same, it is highly important that you are using the right sized solar panels which can properly charge your 12V batteries.

Thankfully, you can use almost any size of solar panel to charge your 12V battery even if it is going to take a long time. That being said, connecting your solar panel directly to a 12V battery will not charge it. Instead, you will need to use a charge controller that offers regulated electricity from your solar panels to your 12V batteries. Such charge controllers also prevent battery issues from things like overcharging.

Apart from a charge controller, you will also need a power inverter that converts the DC current into AC current to be used by your electrical appliances. And for connecting all of these devices together with your solar panels and 12V batteries, you will also need the right connectors and cables.

What is an Amp Hour Rating?

If you are in the market for a new 12V battery, you will find an amp hour or an Ah rating on almost all of them. And this rating is one of the most important things to check since it essentially tells you about the capacity of a given battery. It tells you about the amperage that can be supplied within an hour from your 12V battery.

Apart from getting an idea of the capacity of your batteries, this rating can also be useful to get an idea of the amount of time needed to fully charge your 12V battery using your solar panel as you will see later on in this guide.

How Much Amps does a 100 Watt Solar Panel Produce?

Since you will be using your solar panel along with a 12V battery, you may also want to check the amps produced by a given solar panel. And to understand this better, let us consider a 100-watt solar panel that is connected to a battery.

If you are using a 12V solar panel that is rated for 100 watts, and it is performing at optimal conditions, the actual voltage output will be higher at around 18V. Because of this, a 100-watt panel will offer about 5.5 amps of electrical output as power wattage is the product of the voltage and current. In other words, a 100-watt solar panel will produce 5.5 amps every hour.

How Many Panels are Needed to Charge a 200 Ah Battery?

While buying 12V batteries and solar panels, you may also want to get an idea about the number of solar panels needed to charge your battery. And for this example, let us consider a 200 Ah battery that is connected to solar panels. Starting with the actual capacity of your 200 Ah battery, it will only have 80% capacity as its actual capacity.

In other words, a 200 Ah battery will offer 160 Ah as its actual output. If this capacity usually lasts you for two days, then it means that you are using 80 Ah every day for your battery. Hence, you will need a solar panel powerful enough to charge the battery to 80 Ah capacity every day so that it does not run out.

As mentioned earlier, a 100-watt solar panel will offer 5.5 amps every hour during optimal conditions. But because of environmental factors, the actual output of a 100-watt solar panel will be around 30 amp hours every day. Hence, you will need at least 3 of such 100-watt solar panels or a single 300-watt solar panel to properly charge your 200 Ah battery so that it does not run out if it is consuming 80 amp hours every day.

How much Time is Needed to Charge a 12V Deep Cycle Solar Battery?

Even if you have a powerful enough solar panel that can properly charge your 12V deep cycle solar battery, you may still want to know the time it will require to do the same. Unfortunately, the time needed to charge a 12V deep cycle solar battery depends on a lot of factors.

For starters, the primary factor is the current weather conditions in your area. Depending on the weather, a typical solar panel will charge an average-sized 12V deep cycle solar battery in 5 to 8 hours. If it is a sunny day, then the battery will get charged much faster than it will on a cloudy day. Similarly, your batteries will charge faster during summers than in winters.

Apart from the weather, the current charge left in your 12V deep cycle solar battery will also affect its charging time. This is due to the reason that a fully discharged 12V battery will take much longer to charge than a battery that still has half of its capacity left in it.


Upon going through this complete guide on what size solar panels you need to charge 12V batteries, you must be able to easily select the right type of solar panels for your needs. You can also find various information regarding 12V batteries that are commonly used along with solar panels. In fact, we have also given detailed information regarding the charging time and requirements of most solar panels and 12V battery combinations. If you have gone through all the information regarding what size solar panels you need to charge 12V batteries, make sure to share your thoughts in the comments section. You can also post any questions down there if you have any!

2 Responses

  1. I find Electronics Hub very informative & empowering. I’m now confident to go-green. Gerald from South Africa
    Thank you

  2. Hello – I’m a lithium virgin and this article was very, very helpful. I’m purchasing a fifth wheel in a few months (made by Escape in BC). I’m looking at getting two 100 Ah lithium batteries with two 190 W solar panels for the roof. I may only now get one 190 solar panel on the roof and look at getting a portable 200 W solar panel.

    Thanks again for a great article

Leave a Reply

Your email address will not be published. Required fields are marked *