Flexible solar panel durability/longevity test

tree-damaged roof/awning  damaged panels

The Traveling Cat Adventure Vehicle (my LTV Unity RV) is going off for repairs tomorrow following the damage caused by the fall of a large redwood tree limb.  Besides the roof and awning damage, the tree limb also struck and dented one of my thin, flexible solar panels.  Some time ago, I also damaged one of the panels with a faulty adhesive installation.  So, this seemed like a good time to test whether either of these panels need to be replaced.  I cleaned all six panels (using this great waterless car wash spray) and then set about isolating each pair of panels to test their relative response to the mid-day, mid-November sun.  The six panels are wired up in a parallel-series arrangement: three parallel sets of two panels in series, to boost the voltage rather than the amperage, making use of the original wiring which is turn connected to my Victron MPPT controller that then converts the voltage to an appropriate level for the battery.  (Details on my installation here.)

One pair is the original 100W GoPower panels and the other four are the GreeSonic panels I added (which have an arguably superior EFTE surface material) and use efficient SunPower cells which are also known to perform well in overcast conditions.

Somewhat unexpectedly, it’s the original, undamaged GoPower panels that turned out to be underperforming.  The undamaged GreeSonic pair was producing as much as 7.7 amps (or 106 watts) and the other pair (with visible surface damage) was producing 6.9 amps (or 95 watts).  Since the Unity’s roof is slightly curved, the first pair was angled slightly towards the sun and the other pair angled slightly away from the sun.  So both GreeSonic pairs are really performing about the same.  Keep in mind that the sun’s position in the sky during this test in mid-November was fairly low at about 34 degrees above the horizon, or about 55 degrees off of the vertical of the solar panels. Meanwhile, one of the GoPower panels has failed out right and was showing voltage but no amperage – presumably there’s a short in there somewhere. The other GoPower panel was only delivering 2.0 amps (30 watts) when isolated from its failed companion – compared to one of the “damaged” GreeSonic/SunPower panels on the same sloped side of the RV at 3.5 amps (48 watts).

So, in terms of durability, these flexible GreeSonic panels held up great to the impact of this quite large redwood limb – and the roof and awning didn’t fair so well.  As for longevity, the original GoPower panels are probably about 4 years old while the GreeSonic panels are about 2.5 years old.  (The Unity has been parked in full sun when not in use since I acquired it a little more than three years ago.)

I’m about to sell my Unity (I’m downsizing to a van conversion done by Van Haus based on a 4×4 converted Ford Transit) but I’m going to go ahead and replace the GoPower panels now with some similar, SunPower-based flexible panels – once I get the Unity back from the roof and awning repairs.  I’ll likely go with flexible panels for the van conversion too.

Here’s the pictures of these solar panel tests:

roof and panels  panel test results   GoPower panel  damaged panels

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