How to Test Solar Panel Wattage? (w/pictures & videos)

If you are a homeowner who is considering buying a solar PV system, knowing the output of your solar panel is very vital.

So in this tutorial, I’m going to explain how to test your solar panel wattage, or else the power.

By the way, if you want to learn more about how to inspect a solar panel before buying one, then I recommend you to read our testing solar panel article. It included the points for visual inspection too.

How to test solar panel wattage?

Knowing your solar panel wattage as a solar PV system owner can help you know how many solar panels you need to power your home. If you have powerful solar batteries and need to power large appliances, you will need to know your solar panel capability. The capability of the solar panel is measured by calculating the wattage produced in a certain period. 

The availability of sunlight energy determines your solar panel wattage. When there is adequate sunlight energy, the solar panel will charge the battery efficiently. In such a case, the solar panel will achieve the rated wattage. 

The state of your solar panel also determines how much wattage the panel can produce. If a solar panel has black spots and dust, it will produce the rated wattage. 

Another factor that determines the wattage produced by your solar panel is the positioning of the solar panel. Placing the solar panel in a direct sunlight path ensures the panel absorbs maximum energy from the sun. 

Now that we know what affects the wattage of a solar panel, how do we test the wattage of a solar panel?

You can find the daily wattage of your solar panel by using the rated wattage of your solar panel and the hours your solar panel is exposed to direct sunlight. It would help if you also accounted for the other variables named above in percentage form.

For example, if your solar panel has a rated Wattage of 350watts and you get 6hours of sunlight exposure, then you can calculate the daily wattage of your solar panel by;

350watts×0.65%×6= 1365daily wattage or 1.365kilowatts-hour. 

You can also use a solar charge controller to test the wattage of your solar panel. 

  • Connect the solar charge controller to a solar battery
  • Next, connect the charge controller to the solar panel
  • Check the voltage and the Amps displayed on the charge controller and use it to calculate the wattage of the solar panel. 

For example, if your solar charge controller displays a voltage of 14.7Volts and the amp is 4.2amps then you can find the wattage is found by calculating; 

14.7volts×4.2amps= 61.74watts.

What does the solar panel wattage say?

A solar panel wattage rating shows how much power a panel can produce to power a home. For example, standard solar panels are rated 350watts.

 The rated wattage does not mean the panel will produce the same wattage. The above factors will determine how much wattage your solar panel can produce. 

Since most homes use more than 350watts for a day, you might be forced to buy multiple panels to be able to power your home efficiently. 

 If the wattage calculated  exceeds the required wattage used in a day, your solar panel can power your home for days. 

How to test solar panel wattage - social media flyer

What is a solar panel load tester?

A solar panel load tester, also known as PV Testers are tools used to test the operating condition and efficiency of solar panels. 

As more solar panels with different capabilities are being manufactured, the need for these testing devices increases. A solar load tester can also troubleshoot the problem with your solar panel. They detect the amount of voltage your solar panel produces in a given time.

These devices can also detect when the photovoltaic cells harness more sunlight energy which might make your solar battery overHeat. 


As a homeowner who relies on solar energy to power your home, knowing the wattage of your solar panel is vital. You will need to know how many panels you need to buy to power your home for a given period. 

When measuring the amount of wattage per day your solar panel can produce, factors like the positioning of the solar panel, the efficiency of the solar panel, and the availability of sunlight energy play a key role. 

You can use a solar charge controller to calculate the wattage required to power your home. 

Testing the efficiency of the solar panel has been possible by the use of a solar load tester. 

Was this article heplful?

Yes No

Leave a Comment