Testing competitors - Second episode

Testing competitors - Second episode


One year ago we left our three panels (Solbian SP, Made in China with SunPower cells and Made in Europe with polycrystalline cells) under water writing “We want to see water freezing and then the hot sun of the 2016 spring warm it again. We'll keep you updated.”


Winter did his job and before the summer the pool where the panels were laying was more similar to a swamp than to a pool. We took the panel, washed them and started the final part of the trial exposing them to the sun with shorted contacts, to maximize the current flowing inside the cells.

Dirty panels  Cleaned panels

Quite soon the Made in Europe polycrystalline panel changed its appearance, the hot spot that was visible only from the back enlarged on the front too and other part of the surface started to bend, sign of other overheated regions. In the meanwhile the two SunPower panels (Solbian and Made in China) remained in better shape, even if some rifts became visible in the cells of the Chinese one.

Under the sun again

The final word was anyway the one of the instruments and we measured the panel with the Sun Simulator, moreover we obtained again their electroluminescence to better understand the cells conditions.

Here are the results. While the Solbian panel showed only a small increase of localized defects, the SunPower Chinese panels had a worst fate, with evidence of several enlarging cracks and some cells dark or almost dark (sign of poor efficiency). Moreover the polycrystalline panel were showing vast not working areas, as it was expectable due to the nature of polycrystalline silicon cells. We want here to remind that the polycrystalline panel were showing damages just after some bendings and thus, before the pool test, it did not even follow all the mechanical stress trials of the other two. Simply saying, the polycrystalline panels tested cannot be considered a reliable flexible panel at all.

Chinese 2015

Chinese 2016

Made in China SunPower.

Before and after the trial.

Several damages and some badly working cells.

Solbian 2015

Solbian 2016

Solbian SunPower.

Before and after the trial.

Some increases of localized defects.

Polycrystalline 2015

Polycrystalline 2016

Made in Europe policrystalline.

Before and after the trial.

Vast and serious damages.

The visual differences were obviously reflected in the electrical characteristics, where we registered the following power losses:

Solbian SP: 9% power loss.

Chinese SP: 13% power loss.

European polycrystalline: 45% power loss


Before the weathering the panels had been subjected to strong mechanical solicitation. They have been overbended and we walk on them on a inhomogeneous surface to purposely damage the cells. Nonetheless the SunPower cells showed a good resistance (as it was expected), while the polycrystalline panel demonstrated its unreliability (as it was expected). The real goal of the trials was indeed to study the evolution of the damages with time, which is what really cares if you are going to install panels on your boat, caravan, or roof. As shown in the first report, the Made in China and Made in Europe panels developed a small hot-spot just after one week of weathering, and the following evolution has been shown in this report. Also the Solbian panel had an important power decrease (9%), but what is making us happy is the result of the electroluminescence showing non serious damages and a slow development of the initial mechanical induced cracks.

Both Solbian and Made in China SunPower panel are still in the field. We removed the polycrystalline one to avoid danger of fire.


Solbian EA Srl

October 2016

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Design: Tembo