What Size Solar Panel is Needed to Charge 12v Battery?

How do you know that your solar panel size is the correct one for your 12v battery?

When we find a photovoltaic application that does not have access to the electricity grid, it is necessary to charge batteries to have electricity when there are no hours of sun. For this, a 12V solar panel is needed to charge the batteries.

It is commonly believed that a solar panel to charge a 12V battery should give 12 volts at the panel’s output, but this would never charge the battery. Therefore, the output voltage of the panel must always be slightly higher than that of the battery.

What Size Solar Panel to Charge 12v Battery

It is quite common and helpful to consider that 36-cell solar panels are usually used to charge a 12V solar battery. But surely you also want to have answers to some of the frequently asked questions:

How is it that a solar panel to charge 12V batteries has to have a voltage greater than those 12V of the battery?

Well, it’s actually simple to explain. Imagine that to be able to charge that battery, we need at least 12.5V in terminals, and the panel gives us a current of 8 Amps in the best of cases. Well, if you do the multiplication, it would be giving 100W at most. This is because the battery limits the panel output voltage to the battery charging voltage.

If you take this into account, plus the losses in the regulator, cables, temperature, etc. you can already understand why you have to charge a 12V solar battery with a solar panel that exceeds 5-6 Volts of the battery.

What are 12V Solar Panels recommended for?

The solar panels 12V are common in small installations, such as in solar lighting kits, only necessary to feed bulbs for a few hours. In the world of caravans, it is also very common to use solar caravan kits, all of them at 12V, where the difference between the rest of solar kits is the frequent use of charge regulators that allow charging two batteries separately, normally for charging the Caravan batteries and the other for living area service batteries.

The maximum installation that we recommend at 12V is the one dedicated to powering a small field house for sporadic or weekend use, and it is also a solar panel to charge a 12v battery. The weekend solar kits are those that are designed to be able to charge a refrigerator or bulbs for lighting the place, as well as TV or other small consumptions. In this type of kit, it is required that the battery has several days of charge so that during the weekend, there is enough charge in them for use.

Types of 12V solar panels

  • Small-sized 12v solar panels: These can be classified as 12V solar panels that reach a maximum of 30W. The best applications for these are usually small luminaires that are used for a few hours: electric shepherds, LED signage, alarms with very low consumption, maintaining the battery charge.

The permanent connection of a small size 12V solar panel like these also helps to extend the battery life noticeably as it will remain high of charge most of the time.

  • Medium size 12V solar panels. These solar panels range between 30W and 100W. They are perfect for 12V lighting kits since the power that these solar panels can give is enough to maintain the charge of a battery that can power points of light in a small room or in a remote location.

They are also frequent in caravans due to their size and can give an acceptable power and can be installed on most caravan roofs.

  • Large size 12V solar panels. Finally, the 12V solar panels that offer the most power reach up to 165W, the most common being those of 150W since the price-power ratio is very favorable.  These solar panels can be used to power small homes, even with your refrigerator and usual consumptions such as lighting, TV, computer, mobile phone charges, etc.

It is much more economical and efficient to use 24V panels since their price-power ratio is more favorable.

Relevant aspects of 12V solar panels

There are some aspects of 12V solar panels that are worth keeping in mind:

  • 12V solar panels are resistant.
  • There are monocrystalline and polycrystalline 12V solar panels.
  • Understanding the technical data of a solar panel is important its correct choice.

The 4 Best Solar Panels to Charge 12V Batteries

Below are some of the best Solar panels to charge 12v batteries that allow charging and conserving the energy of 12V batteries to always be ready for operation. Plus, these options are best if you’re new to solar panels.

1. ALLPOWERS 60W Foldable Solar Panel Charger (5V USB + 18V DC Output + Parallel Port) Monocrystalline

It is a waterproof portable solar panel for a solar generator, suitable for a 12v Battery. The folding solar panels allow them to be easily transported on your routes, excursions, trips and outdoor activities to be able to recharge all your car battery, mobile and portable devices using solar energy.

It can be closed and is easy to move, thanks to its folding design. It also includes a solar regulator that allows you to control the input of the charge into the batteries and make their connection easily.

2. Renogy 100 Watts 12 Volts Monocrystalline Solar Starter Kit

It is a Power Starter Kit, and if you’re new and want to get a start in solar, it is the best option you should opt for. This 100W 12V monocrystalline Solar Starter Kit is very common in the use of small and medium-sized installations provides an excellent energy supply; but, they are still 12V and that with a small charge regulator and a battery, you can have a complete solar installation.

3. Renogy Non-Grid Dependent Monocrystalline 100W 12V Portable Solar Panel

It is a portable and foldable solar panel with an integrated stand with a waterproof charger controller for charging a 12v battery.

4. DOKIO 150 watts Solar Panel Kit

It is a lightweight (9lbs) solar panel kit; Monocrystalline with dual USB outputs, solar charger and PV cable to charge 12v batteries of camper RV van. This 150W solar kit incorporates a dual charge regulator that allows charging 2 independent batteries or 2 groups of batteries at the same time.

Our Final Thoughts

As a summary of the above, we can highlight the important characteristics of the 12V solar panels. It is a 32 cell board specifically designed for charging a 12V battery. Due to their small dimensions, these panels are used in small isolated installations such as caravans, lighting, signage, etc.

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