roof cover that allows solar panel to work

[drummo2a]

I want to cover my RV roof with a tarp to protect against sun damage. I also want my solar panel to continue running to keep the battery charged. I put a clear vinyl window in the roof tarp, over the solar panel. I noticed a drop in the amps going to the battery, but everything still seemed to be working. About 2 weeks later the solar charge controller appeared dead. Nothing was showing on the LCD screen. However, I could measure 18-19 volts on the solar panel side. It was a sunny day. If I directly measured my battery it only said 4 volts. Then I peeled the tarp off the trailer and the solar panel charge controller sprang to life and seemed to be charging the battery as it should.


Any ideas why having a vinyl window in my tarp seems to kill my charge controller?


Thanks

 

[Larry-NC]

Infrared

I want to cover my RV roof with a tarp to protect against sun damage. I also want my solar panel to continue running to keep the battery charged. I put a clear vinyl window in the roof tarp, over the solar panel. I noticed a drop in the amps going to the battery, but everything still seemed to be working. About 2 weeks later the solar charge controller appeared dead. Nothing was showing on the LCD screen. However, I could measure 18-19 volts on the solar panel side. It was a sunny day. If I directly measured my battery it only said 4 volts. Then I peeled the tarp off the trailer and the solar panel charge controller sprang to life and seemed to be charging the battery as it should.

Any ideas why having a vinyl window in my tarp seems to kill my charge controller?

Thanks

Umm...Most of the energy captured by the solar panel is in the infrared spectrum, not visible light. Most plastics transmit infrared about as well as the visible spectra, but if you happened to use one of the plastics designed for residential glass, you would be blocking all that energy.

See this window-tint website for example.

 

[drummo2a]

I am not sure what non-visible wavelengths are absorbed by my vinyl. However I was still getting voltage to the charge controller, just not much output to the battery apparently. I'll have to investigate what part of the electromagnetic spectrum is absorbed by the vinyl. It cost me almost $200 for the tarp and vinyl.

 

[5picker]

And... tarping a R/V roof is never a good idea.
Lots of prior posts of those who did and wish they had not.

 

[Larry-NC]

Quick Check

I am not sure what non-visible wavelengths are absorbed by my vinyl. However I was still getting voltage to the charge controller, just not much output to the battery apparently. I'll have to investigate what part of the electromagnetic spectrum is absorbed by the vinyl. It cost me almost $200 for the tarp and vinyl.

Do this Quick Check: Take off the tarp/vinyl and see whether the charge rate jumps or not. Then you know whether to blame the vinyl or start checking the charging system.

 

[NJKris]

Hope your battery didn't get damaged. Getting down to 4v certainly would hurt a lead acid battery.

 

[GoingNoWhereFast]

If your battery went dead the Charge Controller may have been damaged by the solar panels. I would wonder if the battery may have dropped too low during a few days on low sun / rain / clouds and that shut down the controller.



Also your solar panels have to produce at lease 16volts to kick the charge controller into charging the battery.

 

[Boomerweps]

Just watched a YouTube yesterday where a guy tried to test if there was any difference in a folding solar panel’s output placed in a sprinter van windshield compared to outside on the ground using its kickstands for angling.
He could have tested it a bit better but his panels lost about 40% output inside the vehicle.