A few more questions about solar panels...

[Qwazert]

As you may recall...I had some issues with my solar panels/batteries a few weeks ago.
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30348700.cfm

I've since bought a new controller (because the old one would show the batteries as Charged even though they obviously weren't) and I've come across another puzzle....
The controller is a RENOGY Voyager, rated at 20 amps which should be sufficient for my 100W panels.

Here are the details of my solar panels: The first is an offshore-made flexible type...


and the second is a rigid style, like the type you get mounted to a roof...


As you can see, the specs are fairly close and do NOT exceed the ratings on the controller.

Here's the interesting part; when I connect only ONE panel I get a charging current of around 2-3A.
If I connect the second one in parallel, the charging current either stays the same or decreases slightly.

The controller has built in reverse polarity protection and it gives no errors, so I'm 99.9% certain that the panels are connected properly.
So why am I getting LESS current with the second panel connected?
Does the controller sense that less is required because the batteries are fully charged (still connected to shore power)?

[Gdetrailer]

One has open circuit voltage of 22.60V and the other has open circuit voltage of 20.8V

Most likely neither panel has a isolating diode which prevents battery from discharge at night. So, basically the panel with lower open circuit voltage is now drawing power from the panel with the higher voltage until both panels are the the same voltage..

Basically one panel canceling the other panel due to a mismatch in voltage.

Ideally paralleling panels without a isolation diode they should be "matched" in voltage..

You can correct that, but that requires adding a isolation diode to output of each panel and then connecting in parallel..

The drawback of diodes is they drop about .7V for standard diodes and .3V for Schottky diodes.

Otherwise, you could of coarse you can run a dedicated controller on each panel..