I realize series vs parallel has been covered a lot, my situation isn't quite straight forward though so would appreciate advice.
I bought a camping caravan which came with the following 12V system.
1x 4KWH li-ion 12V battery
1x Victron SmartSolar 100/20 MPPT controller
4x 100W mono crystalline solar panels.
Rated max power 100W tolerance +-3%
Voltage at P-max 18.2V
Current at P-max 5.5A
Open circuit voltage 22.7V
Short circuit current 5.89A
Normal operating cell temp 47 +-2 degrees C
Max system voltage 1000V
Max series fuse rating 10A
Operating temp 40 – 85 degrees C
Application class A.
I want to permanently mount the panels on the roof of the camper but only 3 of them will fit, so my thinking is to permanently mount the 3 and then keep one loose which I can place out in the sun for example if camped under trees or on a cloudy day.
If I connect the 3 panels mounted on the roof in series the VOC will be 68.1V and the current 5.5A which is still well within the limits of the controller. If I then add the 4th loose panel also in series, the VOC goes up to 90.8V which get’s close to the 100V max of the controller, this will also leave no room for a margen of 10% - 15% as recommended for fluctuations in temperature. Alternatively can I connect the 4th loose panel in parallel?
The big disadvantage to series connection in my situation is shade on the panels. At some or other points the camper will stand under a tree or get partial shade on the roof as the sun moves around, so I think parallel will work better.
If I connect the 3 roof mounted panels in parallel the VOC will be 22.7V and the amps of the system 16.5A which is well within the limits of the controller. If I then add the 4th loose panel, the VOC will remain the same but the amps will go up to 22A.
From what I read inputting more current in to these controllers is fine as long as you don’t put in more volts, the VOC of 22.7V will be well within the limits so it’s only the 2 amps which will be out of spec and I guess waisted.
Is my thinking and understanding of these things correct and which in your opinion is the better option?