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Flash Test: technical background and importance

Solar Flash Tests (or: Sun Simulator Tests) measure the output performance of a solar PV module and are a standard testing procedure at manufacturers to ensure the conforming operability of each PV module.

Solar flash testing – technical background

The appliance used for measuring the output performance conformity of a solar PV module is call flash test machine or sun simulator. During a flash test the PV module is exposed to a short (1ms to 30 ms), bright (100 mW per sq. cm) flash of light from a xenon filled arc lamp.

The output spectrum of this lamp is as close to the spectrum of the sun as possible. The output is collected by a computer and the data is compared to a exactly calibrated reference solar module.

The reference data is geared to the power output calibrated to standard solar irradiation. The results of the flash test are compared to the data specifications of the PV module type which – in abbreviated form – are printed on the label on the module’s back.

What exactly is measured during the flash test?

Module parameters are measured at standard test conditions (STC). Temperature has a crucial effect on PV module performance. As the temperature of a module increases two things happen. First: the voltage output of each cell decreases. Second: the current output of each cell increases slightly, overall reducing the maximum power output in Watt (Pm (W)) of the module.

The used standards do not necessarily reflect actual operating conditions. A flash test results sheet usually lists all tested moduels and the specific test results. In the example flash test results sheet below (courtesy of  Sinovoltaics), the yellow marked panels indicate Pm(W) values below the tested module type’s minimum 190Wp (at -0% tolerance requirement).  They do not suffice the -0% tolerance requirement and therefore have to be replaced.

Flash test results -

Flash test results –


For further information on the other testing and performance parameters in the table above you will find detailed information in this topic about Solar Panel Output Parameters.

Why use a reference PV module for the flash test?

The reference module is a module of which the exact power is meticulously determined in advanced, mostly in collaboration with a certification body or testing lab of renown quality testing institutions, such as VDE or TUV. With the use of the reference PV module, the flash test can be configured correctly.

Professional solar PV module manufacturers have two reference solar panels available for each power type. The specifications of the reference solar panels have to be tested and determined by a qualified laboratory.

Why is correct calibration of the flash test important?

Only after correctly calibrating the sun simulator, it is possible to accurately measure the PV module’s Current-Voltage (I-V) parameters.

Solar Module Flash Test

Are flash test results provided by PV manufacturers reliable

We wish they were!
As the flash test machine is configured according to the reference module, one can imagine that the flash test can be configured to produce any desired data.

Even though every manufacturer (should) provide the flash test data of all solar panels ordered, performing own flash tests on-site is necessary to confirm if all quality criteria are met.

It is very easy to manipulate flash test results and adjust related output parameters so that they look real.

Tips and further reading:

A way to receive a flash test that is performed by an independent third party, is to have Sinovoltaics perform a Quality Inspection for you.

Download example flash test results (courtesy of Sinovoltaics).

Comment Section

8 thoughts on “Flash Test: technical background and importance

By Daft P. on 25 June 2015

I’m currently buying solar panels from a distributor, however he doesn’t offer me the flash test results of the panels. Do you believe I’m at risk here?

By Niclas on 26 June 2015

Hello, did you ask for the flash test results and were denied the request or weren’t provided them after purchase? If correctly carried out (and also not being manipulated), the flash test data are an important performance statement about the tested modules, also indicating if your modules at the tested point of time performed with the stated power output. If you are in doubt, you should ask for such (genuine) flash test data.

By Umesh Upadhyay on 10 January 2017

Yes, I think it will better to take the flash report to understand the all power value.

By Daft P. on 30 June 2015

In the meantime I’ve receive flash test data from my distributor and every solar panel seems to perform ‘how they should perform’.
But how do I know the flash test data is real?

By Niclas on 2 July 2015

If you don’t have confidence in the accuracy of the flash test data provided by your distributor, well, unless you perform the flash test yourself (or via a trusted representative/ 3rd party quality assurance provider of yours) and properly (correct calibration module/ properly calibrated flash test machine etc.), you can unfortunately not be 100% sure that the flash test data are real. A malevolent manufacturer, distributor etc. could in theory, provided the related know-how, take a flash test list or even a I-V image and manipulate it.

By Pradeep Kumar on 26 July 2016

What is the way of carrying out Flash test in field.

By mukhtar shaykh on 5 June 2017

sir pls tell me module flash test report standard temperature what??

By Vijesh Jaiswal on 15 March 2018

What if manufacturer of SPV module is not in possession of Reference Panel? How would they measure Current Voltage characteristics of Modules under testing/inspection? Though they have IEC 60904 Test Report from accredited lab.

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