What Solar Panel To Get To Charge A 12v Battery

A solar panel can be a good option to charge a re-chargeable 12v battery.

Cars, Rv’s and campervans, motorbikes, marine boats & scooters can all use 12v re-chargeable lead-acid batteries.

The best solar panel to charge 12v batteries in such vehicles is usually a flexible or bendable solar panel.

These solar panels can be installed, uninstalled and transferred easily between uneven surfaces, but have enough output to charge a 12 volt battery.

In this short guide, we discuss the best bendable solar panel brand and model for this function.

Let’s have a look at it …


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Top Rated Solar Panel To Charge 12v Battery List

Best Solar Panel To Charge 12v Battery – Windynation 100 Watt Bendable Solar Panel (on Amazon)


Best Solar Panel To Charge 12v Battery: Reviews

Windynation 100 Watt Flexible Solar Panel

We already reviewed this flexible solar panel in this guide.

But, some of the things that make this a good flexible marine solar panel are:

  • Works at 18 volts and can charge 12 volt lithium and lead-acid batteries – good for RV’s, electric bikes etc. > use it with a solar controller though
  • Can be curved to a maximum 30 degree arc
  • Very lightweight – only weighs 4lbs – easy to transport, install and remove
  • Frameless design, and 6 pre-fab metal reinforced mounting holes which can use temporary or permanent fixings
  • Can be mounted using adhesive or velcro as well
  • Weather resistant
  • Comes with connectors and connector cable

So you know how much room to make space for on your marine vessel:

Panel dimensions are 41.7″ (length) x 21.3″ (width) x 0.1″ (thick)

Where Can I Check This Solar Panel Out?

View the Windynation 100 Watt Bendable Solar Panel (on Amazon)


Best Solar Panel To Charge 12v Battery: Buyer’s Guide & FAQ

What Are 12v Batteries?

12v batteries can be used in a number of applications – cars, boats, rv and caravans, motorbikes & scooters & more.

These batteries are most lead acid batteries, and there are lithium ion batteries as well.

There are many variations of 12v batteries, so they are not all the same.

For example some are regular 12v batteries, and some are deep cycle (which means that use their full capacity at all times).

There is also to consider how much A/H worth of charge the battery uses up per day.

Check the manufacturer’s instructions to confirm the methods the battery can be charged by, and what the recommended power input type and amount is when charging.


What Types Of Solar Panels Are For 12v Batteries?

Flexible solar panels with solar regulators/controllers (to control the output so the panel output doesn’t damage the battery) are the best for charging 12v lead acid and lithium ion batteries.

Flexible panels between 100 to 200 watts are generally best for most 12v batteries that can be charged by a solar panel.

A single panel can work, or some people may choose to purchase 2 x 100 watt panels for example.


What Are Solar Panels Used For On 12v Batteries?

Flexible solar panels can be used to charge re-chargeable 12v lead acid and lithium ion batteries.


What Solar Panel To Get For A 12v Battery – How To Choose?

You want to check your battery is re-chargeable, and can be charger on solar or an inverter first.

To figure out what panels you need, and how many panels you need and the Wattage, generally the following calculations might apply:

Figure out how many hours worth of sunlight you have in the day

Look at how many A/H a day of charge your 12v battery uses

Multiply the A/H of your battery by 12v to get Watts per hour

Divide the watts per hour number by the number of sunlight hours in a day

This will tell you how many total watts you need to charge your 12v battery in a single day, and you buy the number of solar panels accordingly. Make sure you check the actual number of watts your solar panel and regulator set up produces

e.g. if you need 140 watts to charge your battery, it’s probably wise to have two 100 watt panels at the very least

Over allowing is smart because in reality you usually don’t get the full wattage that is stated on the solar panel anyway – it might be 10-25% less in some cases


It is always recommended you check with the panel manufacturer and supplier first though before you buy to confirm your calculations are correct.

Don’t buy the panels without confirming with them about the panels, the conditions you will be using them under, what you’re using them for, and other variables such as regulators and controllers that may effect the setup you need.


Features To Look For On Solar Panels For 12v Batteries

We discussed features to look for in flexible panels in our guide on flexible solar panels.

But, specifically for 12 volt batteries, you want to consider:

The wattage of the panels

The voltage the panel outputs at (usually needs to be at least 13.6 volts for a 12 volt battery)

Check what the manufacturer has specifically designed the solar panel for – charging 12 volt batteries? If so, what types?


Always cross check these features and information with that of your battery.


Solar Panels For 12v Batteries – Accessories

Regulator/solar controller

Extension cables

Inverter (usually not required)


What Size Solar Panel To Charge 12v Battery, & How Many Panels Required?

12v lead acid or lithium ion batteries are common in vehicles like Rv’s, marine boats & yachts, cars, bikes – the list goes on!

But, what size solar panel do you need to charge a 12v solar re-chargeable battery?

And, after determining size, how do you figure out how many panels you need?

The answer is that it depends – on both the battery, and the solar panel set up you are using.

Below we have listed the types of solar panels you might use to charge a 12v battery, and informational guidelines for the size of solar panel required.


*You should always check the battery, and solar panel manufacturer instructions for exact charging requirements & compatibility.


What type of solar panel to charge a 12v battery?

Before we identify the size of solar panel needed to charge a 12v battery, it makes sense to know the type of solar panels you might use.

In some situations where you’ll be charging a 12v battery – like when out with an rv for example – you’ll be off grid.

In these instances, more portable solar panels will be a better choice.

You can read more about both mounted/fixed solar panels and portable solar panels for 12v batteries here.


What size solar panel to charge 12v battery?

Short answer:

One or multiple 100-120 Watt rigid, flexible/bendable or large folding solar panels will usually be a suitable size panel for charging a 12v battery.


More Detailed Answer:

Size could mean two main things with a solar panel – the surface area dimensions, or the size of output (Watts & volts) that it has.

Whilst surface area is important for knowing whether and how many solar panels you can fit on a surface, output is far more important as far as battery charging.

A 12v battery will have two main pieces of information you need to know in order to find out what size panel is required to charge it:

1. How many volts it needs  – a standard 12V re-chargeable battery needs roughly 13.6 volts to charge.

2. How many A/h (amp hours) it needs replaced each day to be fully charged – the battery manufacturer should also tell you the A/h of the battery.


Once you know this information, you can then figure out how many Watt hours you need to fully charge the 12v battery:

1. Estimate how many hours of sunlight you have available to shine on the solar panel/s

2. To get the Watt hours that you need, multiply the battery voltage by the A/h – e.g. with a 110 A/h 12v battery, it would be 110A/h x 12v = 1320 Watt hours

3. To find out how many Watts of solar panels you need, multiply the Watt hours by the hours of sunlight available e.g. if you have 6 hours of sunlight available to you in a day (take into consideration cloud cover too), it would be 1320 Watt hours/6 sunlight hours = 220 Watts of solar panels


So, how do you use that information?

Well, we know that we need 220 Watts of solar panels, but we should also be aware that solar panels in reality don’t produce full output compared to the marketed numbers. So, it’s wise to up that number by 10-20% – to 240-260 Watts of solar panels.

If you want say a flexible solar panel, they come in mostly 50 Watt and 100 Watt models.

A 100 watt flexible solar panel will output roughly 17-19 volts while operating.

3 x 100 Watt flexible solar panels would be suitable in this instance to meet the 260 Watt requirement.



Due to the difference in voltage, a solar controller/regulator should be used with these solar panels to charge the battery to prevent damage to it

Most reputable solar panel manufacturers suggest 3 or 4 stage charging protection between the panel and the battery


How many solar panels to charge 12v battery?

Refer to the answer above – it depends on how much power the battery you have is using per day.





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