Has anyone had any experience with Solar Cynergy 120W Semi-Flexible Monocrystalline Solar Panel? Currently these are selling for 119 at Solarblvd. Seems attractive if they are any good.
Flexible Solar Panels
- Thread starter sea_casper
- Start date
If you get them, buy twice as many as you'll need and plan to return half. In my experience, inexpensive flexible panels are either well-matched to each other or wildly off. I had to buy 7 to get 4 that were well matched. I returned the three bad ones.
Curious about the screening because there are good and bad ways to do this.
Assuming the need for matching is because you are using panels in parallel with a MPPT controller..
This forces the voltage of all the panels to be the same so the important thing for matching is maximum power point VOLTAGE. If you really want good matching, the maximum power point voltage also tracks over temperature.
Screening for short circuit current - does not matter at all. You would generate the most power by picking panels with the highest short circuit current rather than a close group. Open circuit voltage.. this might have some correlation to maximum power point voltage but likely not enough to screen by. It may have more to do with leakage currents - which are in the noise when the panels are generating power.
By far the best screening method would be to hook each panel up to a MPPT controller one at a time holding sunlight and temperature constant, let the controller find the maximum power point voltage and note this. Compare maximum power point VOLTAGE between the panels.
So Im curious.. what parameter makes the flexible panels so bad? If the screening was maximum power point VOLTAGE, good job. If it was short circuit current that was in spec.. you may have sent good panels back to the manufacture.
Assuming the need for matching is because you are using panels in parallel with a MPPT controller..
This forces the voltage of all the panels to be the same so the important thing for matching is maximum power point VOLTAGE. If you really want good matching, the maximum power point voltage also tracks over temperature.
Screening for short circuit current - does not matter at all. You would generate the most power by picking panels with the highest short circuit current rather than a close group. Open circuit voltage.. this might have some correlation to maximum power point voltage but likely not enough to screen by. It may have more to do with leakage currents - which are in the noise when the panels are generating power.
By far the best screening method would be to hook each panel up to a MPPT controller one at a time holding sunlight and temperature constant, let the controller find the maximum power point voltage and note this. Compare maximum power point VOLTAGE between the panels.
So Im curious.. what parameter makes the flexible panels so bad? If the screening was maximum power point VOLTAGE, good job. If it was short circuit current that was in spec.. you may have sent good panels back to the manufacture.
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My concerns about solar panels is not how much output they can deliver but more about how long they will last. Degradation is a factor.
Unlike a rigid panel, the polymer coating on the flexis will haze over due to UV exposure, it's just a matter of when. Back when Renogy sold these, they offered a 5 year materials warranty (no performance warranty) so I'd use that as a baseline. I live in Seattle so I figured mine would be good for 10 years but two years in I'm starting to see some localized blistering where there were fisheyes in the coating. I don't think it's affecting output much yet but I'll be testing next summer and won't be shy about making a warranty claim.
I set up a 10 ohm load resistor with some MC-4 connectors and pigtails to act as test points to measure the voltage across the resistor to determine the current flow through it. I laid all the panels out in a large room with shades I could lower to change the ambient light level and measured the voltage across the resistor, quickly swapping it from panel to panel. Then I changed the light level and did it again for a total of four data points per panel. What I found was that in the end, only one illumination level was needed to ID good versus bad panels. The good ones were remarkably well matched, generally within a few percent. The bad ones ranged from 50% to 20% lower output than the good ones.
In addition, I have fabricated a rectangular piece of Sunbrella, with finished edges that is slightly larger than the panel. I secure the cover over the bimini mounted flexible solar panel with velcro. I use the cover only when I DO NOT need the panels power. Example: alongside when the boat is plugged in and charger is in service.