Combining Fixed Solar Panel and Portable Briefcase

elblueduck

New Member
I am working on powering a camping trailer. It has a roof top tent on it so not a ton of room for panels on the top.

I am thinking that I put 1 fixed panel on it this will charge it while moving and have 1 briefcase panel that I can put on the ground since many times my trailer may be parked in the shade.

Up top without hanging over on either side I have 48 inches of width and 38 of length. I could pick up about 9 more inches if I scrap a small table I have in front of the roof top tent.

If I go with Rich Solar panels the fixed panels could be:
  • Maximum Power(Pmax): 100W
  • Maximum Power Voltage(Vmp): 18.2V
  • Maximum Power Current(Imp): 5.49A
  • Open Circuit Voltage(Voc): 22.1V
  • Short Circuit Current(Isc): 5.93A
  • Maximum System Voltage(Vmax): 600V DC
  • Weight: 16.5 lbs
  • Dimensions: 46.7 x 20.1 x 1.4 in

The suitcase could be:
  • Maximum Power(Pmax): 100W
  • Maximum Power Voltage(Vmp): 18.4V
  • Maximum Power Current(Imp): 5.43A
  • Open Circuit Voltage(Voc): 22.6V
  • Short Circuit Current(Isc): 5.72A
  • Maximum System Voltage(Vmax): 1000V DC
  • Weight: 21.5 lbs
  • Dimensions(folded): 27.0 x 22.0 x 2.8 in
  • Dimensions(unfolded): 43.3 x 27.0 x 1.4 i
So questions I have.
1. Should I put 2 panels on the top? If I did I would either have to tilt them at an angle enough to pick up 2 inches or remove my table from up front or have them overlap slightly? I am fine with the expense of the additional panel as long as it isn't a waste of panel tilting them or overlapping.
2. The numbers on the 2 seem very similar in voltage and current so would I be fine to mix these 2 or would the number need to be even closer/exactly the same?
3. I haven't picked a charge controller yet so if yall have any recommendations that would be appreciated.

So far the only thing I have purchased is the 206ah Sok LiFePo4 battery so if I should pivot some other way no would be the time to do it. We wont be running anything too crazy on this system; a fan, some led lights, dometic cfw 75 fridge, topping off batteries for cameras and headlamps, and maybe in the future a small water pump. I can add pictures if that helps or if people are interested in the trailer, I think its pretty cool.
 

thegoogler

Solar Enthusiast
Re: #1 - I've become a fan of the suitcase method, at least for some of your panels. Fixed is fine if you always have sun (like in a literal fixed setup where your panels are mounted on poles), but if you're camping in the woods your fixed location panels may not get sunlight. However a portable panel allows you to get at least 50% of your power by moving the suitcase to somewhere further away (assuming you have an extension cable).

re: #2 - I have 350W of solar on the roof of my trailer (two 175W panels in parallel, running 12V). Those connect to an MPPT charge controller.

I recently added a 100W flexible panel. It plugs into an SAE port I put in the side of the camper. I move that panel around and reposition it depending on the sunlight (unlike the ones on top which are fixed and might be shaded depending on the location). The SAE port also connects to the panel side of the MPPT SCC. In short they will work fine together, in my limited (and anecdotal) experience, so long as your total power is below the charge controller rating.

re: #3 - The Victron 75/15 would be ideal for your setup as it's good for up to 220W of panels, and LiFePO4 compatible. I think they're running about $120 atm


Side notes: Make sure you have a fuse or circuit breaker on your charge controller, and in your case definitely wire this as 12V (whether you mount both panels on your roof or move one around) as the parallel setup will ensure you get at least some charge when one panel is shaded but the other has sun.
 

jamiko

Solar Enthusiast
I would suggest two MPPT controllers, one for the fixed panels and one for the portables. I would put as many fixed panels as possible. People tend to get lazy about always setting up portables. Then there is security issues if you leave the campsite. Fixed don't walk away, but portables often do.
 

thegoogler

Solar Enthusiast
I would suggest two MPPT controllers, one for the fixed panels and one for the portables. I would put as many fixed panels as possible. People tend to get lazy about always setting up portables. Then there is security issues if you leave the campsite. Fixed don't walk away, but portables often do.
I'm curious why two controllers?
 

jamiko

Solar Enthusiast
I'm curious why two controllers?
Well maybe not needed. It depends on wiring and voltages. Those panels are very similar on volts and current. I was just thinking longer term if the OP adds fixed panels in series and tries to join with the portable. The portable will likely have a better angle and different output. Just don't want the portable to lower the performance of the fixed panels or vice versa.
 

thegoogler

Solar Enthusiast
Ah ok, I wasn't sure if there was a specific compatibility issue or if two differing panels might mess with the MPPT algorithm.

His setup sounds fairly small and unlikely to grow significantly. I'd personally start with a single Victron 75/15 and if there was a desire to move to 24V in the future then buy the second controller at that time. But then I'm cheap and tend not to buy once, cry once, so to speak.
 
Top