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Can I Use an 18v Solar Panel to Charge a 12v Battery?

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What distinguishes solar panels with 12 and 18 volts? Most of the time, there are no differences. Early solar panels tended to be frequently used as a simple direct connection to a 12V battery for charging.

Any battery you link the solar panel to will have the same voltage as the battery.

If the battery’s voltage is higher than the open circuit voltage, the solar panel won’t produce any electricity and won’t be able to charge the battery.

If more than six cells are shaded, an 80W panel will output between 16 and 18 volts, which means it will be unable to charge a 12-volt battery directly.

There are other steps you can take to charge your battery as a direct connection between two devices (different volts) that aren’t compatible could be disastrous!

Can You Attach a Different Volt Solar Panel Directly to the Battery?

Under ideal conditions of direct sunlight, an 18v solar cell will generate 22–25 volts. So, you can connect different voltage solar panels to the battery if you’re employing a 5W solar panel, which means a 12-volt battery can be charged using an 18-volt solar panel.

Now that the voltage has dropped to between 24 and 25 volts, how can you use the solar panel’s 24-volt output to recharge your 12-volt battery?

Well, the voltage generated by the solar panel must be controlled by a charge controller for solar panels larger than 5 watts to power the battery.

You mightn’t want the battery could sustain long-term damage due to dealing with a solar panel with an output of more than 5W. Directly connecting a different-voltage solar panel to a 12-volt battery can cause the battery to become permanently damaged.

How to Connect A 18v Solar Panel to A 12v Battery?

Depending on the built-in rechargeable’s type and state of charge, 12V batteries can be imposed at 12V (up to 14V).

When a battery is discharged, it will accept higher voltage, but as it is recharged, the input voltage limit will drop.

Therefore, connecting the 12V battery to the 18V solar panel directly has a risk of permanent damage to the battery.

Keep aware that the warranty does not cover this type of damage. The following devices can be used to charge various solar panel sizes from a 12-volt battery.

Make Use of a Charge Controller

The amount of current and voltage sent to the loads are controlled by the charge controller. If you’re installing an off-grid solar process with batteries, you must always use a solar charge controller effectively.

A charge controller will reduce the 18 volts generated by the solar panel to 12 volts for battery recharge, allowing the battery to be charged. Two distinct kinds of charge controllers are PWM and MPPT, which is better?

  • PWM (Pulse Width Modulation) charge controller

Consider a PWM device as a switch that connects the battery and solar panels. While the charger technique is set to bulk charge, the switch is on.

A PWM charge controller keeps the amps constant while lowering the greater voltage from the solar cells to match the battery voltage.

To calculate amps, an 18V 100W solar panel will generate 25v (open circuit voltage) in ideal sun conditions (100/25 = 4.1 Amps). An 18v 100w solar array will supply 4.1 amps.

The PWM controller thus reduces the voltage to 12 volts while maintaining the same number of amps, resulting in a 50-watt output.

  • MPPT (Maximum Power Point Tracking) charge controller

The MPPT controller assures the battery receives the maximum amount of current to be utilized. It controls the voltage when the loads receive the most power while experiencing the fewest losses.

Its internal mechanism adjusts the solar panels’ voltage output by the battery’s voltage while also increasing the amps, making them 30% more effective than PWM Charge controllers.

Use an MPPT controller if you have an 18-volt, 24 volts, or even 48-volt solar panel to power your 12-volt battery.

Utilize a DC-DC Converter

A DC-DC converter resembles a less expensive charge controller. The transformer will also reduce the high voltage from the sun’s rays to 12 volts so that a 12-volt battery can be charged.

But they will result in a power loss, just like PWM charge controllers.

If you’re using a big-size solar panel, the difference will be significant. However, you can use this device with a 20W or 50W solar panel. You will still experience some power loss, but it won’t be significant.

How Quickly Can a Solar Panel Charge a 12v Battery?

Depending on a battery’s condition, the overall charging time may vary. A 100-watt solar panel will take two hours to replenish an average 12v 50Ah auto battery.

A 100-watt solar panel will take about 4 hours to completely recharge 12v 50Ah lead-acid batteries that are 50% discharged.

It will take five hours to fully charge 100 amp-hour batteries at 12 volts, 20 amps. Installing a 300w solar panel because 20 amps times 12 volts equals 240 watts, which is the size of a panel you would need.

Can You Connect a 24v Solar Panel to a 12v Battery?

First determine whether your solar panel runs on 12V or 24V, by searching on the back of the instrument or in the owner’s manual, search for the label. To determine the voltage, you might set up a multimeter.

Technically it is possible to charge a 24V solar panel with a 12V battery but it’s not a good idea to think about utilizing this. For on-the-go RV battery charging, a 20W solar energy system is ideal. Your RV batteries can be charged more effectively by using a 20-watt solar array and controller.

Can a 12 Volt Solar Panel Charge a 6 Volt Battery?

A single 6-volt battery can’t do this. You will need a minimum of a 12-volt battery pack to charge a 12-volt panel.

You can utilize 6-volt batteries, but you’ll require at least two of them connected in series.

You may utilize a 12-volt battery pack if you have a pair of 6-volt batteries linked in series. The voltage of two batteries connected in series is increased while maintaining identical amp hours.

The negative end of the first battery should be connected to the positive terminal of the additional battery.


A solar panel can overcharge a battery. The battery voltage, output current, and solar panel voltage all affect how quickly batteries charge. By employing a charge controller, overcharging may be prevented.

A 12V battery requires at least 14V to be charged.

You may utilize an 18v or 24v solar panel to power a 12v battery with the aid of a charge controller or DC-DC converter; an MPPT charge controller will be more effective in this situation.

Utilize the Luminous NXG 750, a hybrid inverter that supports solar panels with a voltage of 12V and a power output of 400W, based on their details. If you have further query ahead, please contact us.