How To Test Solar Panels Without Sun: Step-by-step guide

Solar panel testing is a mandatory step to determine the efficiency and quality of your solar panels. Like most other electronic gadgets, solar panels are also put under a few specific testing procedures to get a green light for industrial use.

Most solar panels have a nice and long lifespan of nearly 25 to 27 years, provided they are properly manufactured and installed.

So, when you are about to install your very own, self-sufficient power station which will generate electricity for your home or workplace for the next 25-30 years, you must be looking for the best option within your budget. Solar panel testing is ultimately a way to get an idea about panel safety and quality. 

Since you’re here, you know solar panel testing is crucial for many reasons. 

But are we able to test solar panels without sunlight? 

Yes, we can test solar panels without sunlight. Although solar panels need sunlight to perform their job, they are also sensitive to other forms of visible light. Photons in the sunlight hit the PV panels, releasing electrons. The flow of free electrons thus results in the production of electricity. So, artificial light containing enough power can free electrons sufficiently to test the solar panels. 

Why is solar panel testing necessary?

Most of you may know the importance of solar panel testing. But we will start from scratch. Solar panel testing helps us to check minimal quality standards and performance of the panels under ambient stress.

By testing your solar panels, you can ensure that your panels meet up to the required safety precautions. IEC (International Electrotechnical Commission) advised that we must periodically check the universal standards for PV panels.

Solar panel testing is a crucial part of their maintenance to maintain the suggested standard of performance and quality. The USA also has its authority, the United States National Committee (UNSC), that ensures solar panel safety and quality. Also, to prevent the risk of malfunction, physical damage, or dirt contamination, you need to test your solar panels every once in a while.

Can you test solar panels without Sun?

Solar panels work under sunlight. The best way of getting the optimal performance from your panels is, above all you need to place them under adequate sunlight. So, the general idea of solar panels revolves around the Sun, and we all know it. 

But to tell you the amazing fact about solar panels, they can function without the Sun. Yes, you can test your solar panels without Sun! 

Solar panels work finely on a cloudy day or during winter when direct sunlight is absent. Not only that but also solar panels work under intense artificial lights. Though charging your solar panels using artificial light is not a good idea, it will be a waste of energy by all means! But, you can safely use artificial lights having a spectrum similar to the Sun only to test your solar panel. 

To test your solar panels without Sun, you can use an incandescent or a fluorescent light with high energy. This type of light is highly recommended. 

Step-by-step guide to testing your solar panels without Sun

You can test your solar panel wattage to see if the panels are working correctly. Follow the steps below to test that your solar panels pass the minimum quality and safety standards.

Step 1

Solar panel wattage is given by Wattage= Volt* Ampere 

To test your solar panel wattage, you must first bring intense artificial light near the panels. 

Step 2

To measure the voltage across the panels, connect a voltmeter parallelly. 

Step 3

Check the voltmeter reading. If it shows some reading, then your panels have started to work. 

If your voltmeter reading is too low or even zero at this step, don’t panic! Your panels are not inefficient! It’s just because artificial lights are not powerful enough as sunlight.

Step 4

Measure the electricity produced by the panels with a multimeter. 

You can test your panel wattage through this process. Then you can say if your PV panels are in working condition. As we just want to test the minimum quality and performance of the panels without the Sun, we use artificial light, and it’ll not show you the optimal performance of your PV panels. 

What specifications do we need in case of artificial light?

Incandescent/fluorescent light is a good choice for solar panel testing. But the performance and output of your solar panels will never be the same as they are under sunlight.

Also, when using artificial lights, the performance and output of your solar panels depend on various things. The type of light, warm or cold light, intensity, and wavelength of the light all matter a lot to get the desired result. 

Now the artificial light you’re using must resemble the Sun’s spectrum. The energy coming from the Sun is classified in a light spectrum spread from Ultraviolet to Infrared. The graph below shows Spectral irradiance vs. Wavelength of light.

 

The solar panels absorb the visible light mostly. From the graph, we can see sunlight has maximum energy in the visible light region. So, we must choose artificial light closer to this wavelength range to get the most out of it.

How are solar panels tested in the factory?

In the factory, solar panels are tested right after production. They are tested under certain conditions known as “Standard Test Conditions” (STC). In STC, the tester light source is calibrated to a specific wavelength, and the temperature of the whole system is kept at 25°C (77°F).

During the testing, solar panels are connected to a measuring device and then put under powerful artificial lights. Panel voltage, current, and wattage, everything is measured through the connected measuring device. Thus, a general idea is obtained from this test of how these panels will work in reality. 

But STC doesn’t seem like the real atmosphere out there, so another testing standard was introduced. PVUSA or ‘Photovoltaics for Utility Scale Applications’ or popularly known as PTC. In the PTC testing method, panels are kept at 45°C, which seems rational.

Under the sunlight, the panel temperature gets as high as nearly 45°C. Also, a breeze of velocity 1meter/second blows across the panels to make the testing setup more realistic. The ambient temperature is fixed at 20°C (68°F). 

By PTC testing, manufacturers can produce appropriate panels for the real world. The performance of a solar panel is also more accurately checked under PTC testing conditions.

Why is sunlight always preferable?

Sunlight has an illuminance of roughly 98,000 lux or lumens per square meter when it falls perpendicularly on a surface (at sea level). In areas that receive direct sunlight, we can get almost 30,000 to 130,000 lux light levels.

And places outside the direct sunlight area, also about 10,000 to 30,000 lux light levels we get during daytime. This is huge. We can not provide the same amount of energy as sunlight by any alternative method, and it’s just the energy conservation law.

The light energy we get from any 100-watt incandescent bulb is very low, and most of the energy it radiates is heat energy. 

So, using any artificial light or other light sources cannot do our job here. Sun is the ultimate energy source, and placing them under sufficient sunlight is the only mantra to get the best performance and highest output from your panels.

Conclusion

Solar panel testing is a responsibility that comes with your Solar Powering System. You frequently check the panels to see if they are working properly. Though it is always best to check your panels under the sunlight, we can also test solar panels without the Sun.

You often need to be sure about the panel safety and minimum quality of performance of the panels. In this case, testing your solar panels without the Sun seems logical and needful.

You can test your panels with artificial lights at home without getting into any trouble of being electrocuted or harming the devices. Because testing your solar panels without the Sun will only provide you the idea if they are safe to use further. The amount of electricity production will be negligible, so you don’t need to worry! 

Be safe and test your solar panels even without the Sun with the help of this article.