What Can a 40-Watt Solar Panel Run?

Do you have a 40 watt solar panel and are wondering what you can use it to power?

40 watt solar panels are portable, handy to carry with you to run light electronics like phones, LED lights when on a camping or a hiking trip.

Unfortunately, they only provide limited power and if you are new to solar, it may not be clear what appliances can be powered with the generated energy.

So, in this article, you will learn about the common appliances that can be powered by the 40-watt solar panel, how to connect these appliances safely and reliably and what battery sizes you should consider charging this solar panel with.

What Appliances a 40-Watt Solar Panel Can Run

A 40-watt solar panel generates between 120 – 200 kWh per day depending on the number of sunshine hours your location receives and can provide power to run the following appliances:

Note: The list is not exhaustive


  • recharge batteries
  • portable solar generator
  • portable power bank
  • solar LED lights
  • LED lights
  • Charging phones, tablets, laptops (connected to portable solar generator or power bank).


Appliances with a high power draw like power tools, fridges, TV, or large capacity batteries are not suited for connecting to solar systems powered by a 40 watt solar panel.

It does not supply enough power for them to charge fast enough or run them.

You may also be interested in: How much power a 200 watt solar panel produces

Can You Connect Appliances Directly to The Solar Panel?

No, you should not connect appliances directly to the solar panel. The power output from the solar panel is not regulated and varies depending on the amount of sunshine the panel receives which is not suited to many appliances.

Instead, you can connect the solar panel to a charge controller to charge a battery, a portable solar generator, power bank, or a solar inverter.

Whichever device you connect the solar panel to should be designed to receive the solar panel voltage and have the right connector type for the solar panel to connect to.

What Voltage a 40 watt Solar Panel Supplies

A 40-watt solar panel is typically rated 12V but supplies about 18V when exposed to sunlight. Make sure that the devices it plugs into can handle about 20V or higher to avoid damage to them from excessive voltage from the solar panel.

How to Run Appliances with a 40-Watt Solar Panel |Does it Need a Charge Controller?

Depending on your solar system setup, the 40 watt charge controller may not need a charge controller. An example is if it is plugged into a portable solar generator, portable power bank, solar LED lights, or solar inverter.

Note, these appliances usually have inbuilt charge controllers to regulate the battery charging process.

How to Use a 40-watt Solar Panel | Which Solar Charge Controller ?

You can use a 4 amp or 50W PWM solar charge controller or a higher-rated charge controller with this solar panel if you have plans to grow the capacity of your solar system.

Can a 40-Watt Solar Panel Charge a Battery?

A 40 watt solar panel connected to a charge controller can be used to charge AGM, Lead-acid, or Lithium batteries provided that it supports and is configured to set the battery type connected to.

Which Battery is Best for a 40-Watt Solar Panel?

While you can charge several battery capacities with a 40-watt solar panel, a 20 Ah AGM or 10 Ah Lithium is probably best suited for this size of the panel.

It will generate enough power to replenish the charge in the battery in about a day if it has been discharged up to 50% of its capacity for AGM and 80-90% of its capacity for Lithium.

Note: This assumes a location with about 3-5 hours of sunshine.

How Many Batteries Can a 40-Watt Solar Panel Charge?

A 40 watt solar panel can charge 1 x 20Ah AGM, or 2 x 7Ah AGM batteries in parallel in about 8 hours depending on the amount of sunshine shining on the solar panel if the batteries have been discharged up to 50% of their capacity.

If the batteries have been discharged by more than 50% or they are larger capacity batteries then they can take longer to charge fully.

How Many Amps Does a Solar Panel Generate?

A 40 watt solar panel can supply about 2.3 amps at peak. Under conditions of cloudy weather, the panel current reduces significantly.

Final Word

40 watt solar panels are lightweight, sometimes foldable solar panels convenient to provide power for light electronics on a hiking or camping trip.

Unfortunately, they can only provide limited power up to 120 – 200Wh of energy per day depending on the hours of sunshine received at your location.

With this energy, you can charge 1 x 20Ah AGM, or 2 x 7Ah AGM batteries in a day, assuming they have been discharged up to 50% of their capacity at a location receiving 3-5 hours of sunshine.

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