How to Test Solar Panels? (A Basic Guide)

If you own solar or are thinking of buying solar panels, you may have already considered testing them. 

But why should you test solar panels in the first place? 

Even though most solar panels are manufactured without a hitch, there is always the possibility of defects. 

Any issues relating to a panel can severely impact its maximum power output and thus energy production. 

By testing your solar panels, you'll get a good idea of whether or not your panels are performing at their optimum capacity.

The question is, how do your properly test your solar panels? 

In this article, we aim to show you how. 

Why should you test your solar panels?

test a solar panel with a multimeter

There are 6 main reasons that testing your solar panels is important: 

  • IEC 62446 compliance
  • Effective grounding
  • System performance verification
  • Avoiding a fire risk
  • Warranty fulfilment 
  • Identifying contamination 

As you can see from the list above, these are pretty important points. Let's dive into each point a little bit further.

IEC 62446 compliance

This standard dictates the minimum requirements for corrective, preventive and performance-related maintenance of PV systems. If you buy a solar panel that has not been put through the IEC 62446 compliance test, you are asking for trouble.

Effective grounding

It is absolutely paramount that solar panels, and their racking systems are grounded. If your system is not grounded you could be at risk for electrical shocks and fires. In very rare instances, grounding systems are capable of degrading. This is why it is important to double check by testing your solar panels.

System performance verification

This is perhaps a no brainer, but, homeowners can spend upwards of $20,000 on their solar systems. It stands to reason that you want the absolute most out of your system to benefit from the solar savings ion order to decrease your ROI as much as possible. Testing your panels allows you peace of mind that you are indeed getting the most out of them.

Avoiding a fire risk

Solar panel fires are rare. Previous reports show that they are lower than 1 incident per 10,000 installations. Nevertheless, according to the SEIA, "Residential solar installations totalled 4.2 GWdc in 2021, setting an annual record and exceeding more than 500,000 projects installed in a year for the first time." meaning out of those 500,000 installations approximately 50 could potentially catch fire. Testing your panels will ensure there are no defects and decrease your chances of experiencing a fire outbreak.

Warranty fulfilment 

Most solar panels come with a 25-year performance warranty. If you happen to test your panel and find that its performance is inadequate, why not make use of the warranty? if you never test your panels you may never be able claim the much needed warranty openly available to you.

Identifying contamination 

Another reason testing can be important comes down to plain old dirt/contamination. A lot of the times, depending on where you live, solar panels can become dusty, covered with all sorts of things. Anything that interferes with the photovoltaic effect will cause you solar panel to produce less electricity. 

Do you know how to test your solar panel? 

healthy and safety inspectors looking at solar panels

Now that we have covered the importance of testing your solar panels, the questions remains. Do you know how to? First things first, if you don't already have a multimeter, you need to go ahead and get one right now. 

Method 1: Test open circuit voltage (Voc)

First things first, you need to located the stipulated Voc of your solar panel. This will generally be found on a sticker at the back of your panel. For example, your open circuit voltage may read: 19.83V. 

Now set your multimeter to measure DC voltage. Make sure to place your panel in full sunlight (remember to angle it towards the sun as best you can). 

Now it's pretty simple. You need to touch the red (positive) probe pin of your multimeter to the positive MC4 connector of the solar panel, and you need to do the same for negative (black)  probe to the negative MC4 connector of your solar panel. 

Now take a look at what your multimeter is reading, does it achieve the stipulated Voc of 19.83V (or your equivalent)? It should be close, but does not need to be identical. 

Method 2: Test short circuit current (Isc)

Located the stipulated Isc of your solar panel. This will generally be found on a sticker at the back of your panel. For example, your short circuit current may read: 6.56A. 

Now set your multimeter to measure amps. (Please note: you need to make sure your multimeter’s fuse size is greater than your panel’s short circuit current.) 

Now place your panel in full sunlight (remember to angle it towards the sun as best you can). 

Touch the red (positive) probe pin of your multimeter to the positive MC4 connector of the solar panel, and do the same for negative (black)  probe to the negative MC4 connector of your solar panel. 

(Please note: you may witness a spark when completing the circuit. This is normal.)

Does your Isc measure up with what the panels sticker reads? If it is similar to what the sticker says, your are in the clear! If you get back something very different, there could be something amiss with your panel (assuming it is a perfect sunny day outside). 

Method 3: Testing solar panel output

To calculate the power output of your panel, you need to multiply the amperage by the voltage. So for example, if your panels Voc is 19.83V and the Isc is 6.56A = 19.83 x 6.56 = 130 Watts. 

Of course your panels wattage will be underperforming if any of the above two methods are off. Nevertheless, it is still interesting to learn your panels exact power output. 

Final thoughts

After reading this article we hope you have a much better idea on how to test your solar panel/s. 

This was just a brief introductory to testing solar panels. At a later stage we may add some further video instructions to this article.  

(It is important to note that should you get a solar panel installation, it would be the on-sight electricians job to test for above. So make sure they go ahead and do so.)