How to Test a Solar Panels Output

Solar panels can lose efficiency over time due to factors such as dirt, dust, debris build-up, and temperature changes. They also can develop problems such as cracks or delamination, which can further reduce their output. 

For this reason, it’s important to test your solar panels regularly to ensure they are performing at their peak efficiency.

This guide shows you three ways to determine your solar panel’s output.

Note: As the power output of a solar panel varies depending on the amount and intensity of sunlight it receives, you should therefore test the production at different times of the day and in various weather conditions.

Method 1: Test a Solar Panel’s Voltage

Note: Ensure that your solar panel is receiving direct sunlight. If it is not, the test will not be accurate.

  1. Set the multimeter to the DC voltage setting.
  2. Connect the positive lead (red) of the multimeter to the positive terminal (red) of the solar panel and the negative lead (black) of the multimeter to the negative terminal (black) of the solar panel.
  3. Take the reading from the multimeter. This is the output voltage of the solar panel. Compare the voltage output of your multimeter to the one listed on the back of your solar panel.

Method 2: Test a Solar Panel’s Amps

  1. Set your multimeter to measure DC amps. This is usually done by turning the knob to the “A” or “10A” position.
  2. Connect the leads of your multimeter to the positive and negative terminals of the solar panel as we did in the previous method. When you connect the multimeter to the solar panel, there is likely to be a spark.
  3. Take a reading of the current flowing through the solar panel and compare it to the one listed on the back of your solar panel.

Method 3: Test Solar Panel’s Wattage

  1. Connect the positive lead from the meter (red) to the positive terminal of the solar panel (red), and connect the negative lead from the meter (black) to the negative terminal of the panel (black).
  2. Turn on the solar panel and wait for the readings to stabilize. Then, take note of the watts being produced.
  3. Check the reading on display. It’s recommended to take multiple readings over a period of time to get a more accurate reading of the panel’s output.

How to Test Cracks or Delaminations in Solar Panels

Using Thermal Imaging to Inspect Solar Panel Installations
Using Thermal Imaging to Inspect Solar Panel Installations by Test Meter

If you’re trying to detect a problem with the panel, such as a crack or delamination, you will need to use an infrared camera.

  1. Point the infrared camera at the solar panel, and take a picture.
  2. Compare the picture with a picture of a healthy solar panel.
  3. This could indicate a problem if you notice a hot spot on the panel.

How Often Should You Test Your Solar Panels Output?

  • Check the output of your solar panels at least once a year.
  • Test your solar panels after severe weather events, such as hailstorms, heavy rains, tornadoes, or hurricanes, to ensure they’re still in good condition.
  • Keep an eye on the performance of your system over time, and have it checked by a professional if you notice any decline in its output.
  • If you have a grid-connected system, your utility company may require you to have it checked and certified annually.
  • If you live in an area with lots of dust or pollen, you may need to check and clean your panels more often.

  • Nichole Hutt

    Hi, I'm Nichole! 👋
    I always felt close to nature during my childhood. Preferring to spend my time alone playing with backyard animals at my family farm. 🐷
    In 1997, I attained my electrical engineering degree at the Oregon Institute Of Technology, graduating top of my class. Several years later, I qualified for my M.S. in Renewable Energy Engineering, also at OIT. 🎓

    Combining my love for nature and passion for engineering, I have worked for solar panel manufacturer's in my state, most notably as a PV solar engineer for Zamp Solar.

    I founded RenewableSystems to share my knowledge and expertise in the renewable energy field and help save this beautiful little planet of ours. ☀️🌎

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