Adding Additional RV Roof Solar Panels Both Series + Parallel?

[jesfl]

Good afternoon Forum participants,

Given the consistent problems I’ve managed with nearly every previous phase of my RV solar system installation and upgrades over the past 3 years, I am herewith trying to avoid another self-inflicted headache, if not a wound.

Right now my system is running great, but I need more solar charging as winter sets in. The need for additional charging is a result of adding a small residential refrigerator last spring and the need for my inverter to run 24/7.

So, I am in the process of doubling my solar panel wattage on the roof of my RV from 600 watts to 1200 watts (that will be a total of 12 100-watt panels). My six existing panels are wired in series. My plan is to wire the six additional panels in parallel.

My thinking is that the two separate “systems” will be a reasonable test of whether the series-wired-panels set or the parallel-wired-panels set gives me better charging the way I use my RV. And, during the summer, I'll only need to use 1/2 of the panels.

To accommodate the additional panels, I am adding a new/additional 40-amp solar charge controller and an additional/separate breaker for the new incoming solar panel wiring.

Does my 600 watts series + 600 watts parallel of solar panels make sense?

What problems does this two-separate-side setup create? (I figure I can always rewire.)

What am I missing?

All thoughts, suggestions and/or especially danger warnings will be valued.

By the way, I spent several hours this afternoon searching the Forum And, again, got completely overwhelmed and lost with the way-beyond-my-knowledge discussions I was able to find.

Thanks in advance to everyone in this Forum.

jesfl

 

[12VoltInstalls]

My thinking is that the two separate “systems” will be a reasonable test of whether the series-wired-panels set or the parallel-wired-panels set gives me better charging the way I use my RV. And, during the summer, I'll only need to use 1/2 of the panels

You’ll be better off buying less costly 300W panels, putting them in 4S or 2S2P through a separate charge controller. Flat panels take you only so far. Vertical often is better

 

[jesfl]

Thanks for responding. Yes, I know the larger panels would be better, and I drooled for them. But, I say sadly, I already had 8-100 watt panels roof-flat-mounted (2 of the 8 were not wired, long story). The only affordable-for-me panels back in 2019 were the 100-watt panels. Fast forward to three weeks ago when the least costly solution was to add 4 more (now much cheaper) 100w panels. Those additional four are now roof-tilt-mounted and ready to be wired. Also, I already owned a second 40-amp charge controller, another long story. I'm pretty sure I've made nearly every possible mistake during my RV solar system journey.

So the two separate charge controllers idea will work OK, I infer from your "through a separate charge controller" comment?

Are you also suggesting serial panel wiring is better than parallel?

Again, thank you.

jesfl

 

[12VoltInstalls]

So the two separate charge controllers idea will work OK, I infer from your "through a separate charge controller" comment?

Yup. I need to finish up my intended install, but I have three running together right now.

Are you also suggesting serial panel wiring is better than parallel?

Not sure of your latitude, but: in my experiments the higher string voltage wakes up the SCC’s a little earlier in the day, and it ‘y’ that cloud days performance is slightly better.