rvupgradestore.com Composet Products Fridge Defend
RV Life Magazine RV Park Reviews RV Trip Wizard

Author Topic: combining portable solar with roof mounted  (Read 512 times)

rbTN

  • ---
  • Posts: 113
combining portable solar with roof mounted
« on: January 14, 2020, 06:21:28 PM »
I just added a 300w Renogy system with the Rover 40amp MPPT controller (which seems to be doing really well so far in my test "driveway camping"). I am trying to decide if I want to add a 4th 100w panel to the roof or go with a portable to be take more advantage of being able to angle it to the sun. The 300w would bring the batteries back to 100% each day after spending the afternoon/night in the travel trailer when outdoor temps dropped to the 30's each night (middle TN in December), so the furnace was def. running, plus I pushed it by having the TV on the inverter (cheap ole 150w model) for a couple hrs each night. I did this 2 days in a row to see how the panels were doing recharging the batteries. They seemed to do pretty well, but I'm sure another 100w would reach float faster and maybe get them to true full charge each day.

I am probably over thinking this, but what is the best way to connect a portable solar kit to a travel trailer where I have 300w solar on the roof with 40amp mppt charge controller?

Do I connect the portable to the charge controller PV in (with the lines from the roof mounted panels) or just use it like it was designed and connect it to the batteries directly?

I'm thinking it would be better to add it to the input of the charge controller so I get a total input higher, rather than it essentially working against each other since both would be supplying current.
middle TN
was - 2001 Ram 2500 4x4 5.9 cummins, auto, camper pkg, trailer pkg (still have the 2001)
now - 2014 Ram 2500 6.7 Cummins, CC long bed SLT 4x4
2007 Thor Denahli 26RL
Equalizer hitch
300 watt Renogy system with 40amp mppt Rover

Gene50

  • ---
  • Posts: 154
Re: combining portable solar with roof mounted
« Reply #1 on: January 14, 2020, 11:35:36 PM »
Connecting your  portable solar panel directly to the batteries will backfeed your solar charge controller with a false high voltage. 

That Will likely cause the solar charge controller to shut off any charging from your roof mounted solar panels.

I wouldn’t do it. 





2011 F350 Lariat 6.7PS
2015 Dutchman Denali 262RLX

TonyL

  • ---
  • Posts: 185
Re: combining portable solar with roof mounted
« Reply #2 on: January 15, 2020, 02:33:26 AM »
Don't connect the portable panel to the existing controller, because if the roof panels are in shade, it will affect the performance of the portable panel. Better to use a separate controller and wire it in parellel to the output of the fixed controller. As someone said on here in a previous thread, it will be like two hoses of different flow rates filling a pool.

solarman

  • ---
  • Posts: 381
Re: combining portable solar with roof mounted
« Reply #3 on: January 15, 2020, 12:18:40 PM »
I just added a 300w Renogy system with the Rover 40amp MPPT controller (which seems to be doing really well so far in my test "driveway camping"). I am trying to decide if I want to add a 4th 100w panel to the roof or go with a portable to be take more advantage of being able to angle it to the sun. The 300w would bring the batteries back to 100% each day after spending the afternoon/night in the travel trailer when outdoor temps dropped to the 30's each night (middle TN in December), so the furnace was def. running, plus I pushed it by having the TV on the inverter (cheap ole 150w model) for a couple hrs each night. I did this 2 days in a row to see how the panels were doing recharging the batteries. They seemed to do pretty well, but I'm sure another 100w would reach float faster and maybe get them to true full charge each day.

I am probably over thinking this, but what is the best way to connect a portable solar kit to a travel trailer where I have 300w solar on the roof with 40amp mppt charge controller?

Do I connect the portable to the charge controller PV in (with the lines from the roof mounted panels) or just use it like it was designed and connect it to the batteries directly?

I'm thinking it would be better to add it to the input of the charge controller so I get a total input higher, rather than it essentially working against each other since both would be supplying current.


two ways,

1. you purchase a second, suitably sized charge controller, connect your portable panels to it and connect the charge controller
to the battery bank. simplest method, also permits you to have different panel types as portable units.

2. connect the portable set to the existing array, only advisable IF:

a) the portable set matches the array on the roof
b) your existing charge controller has capacity for the extra wattage..

here is an example:

   you have 4 panels, 100 watts each of an identical type connected as a 2S2P array.. two series and two sets in parallel
   you make the portable set identical to one string of the roof.. so two panels in SERIES.
   the portable panels may now be connected in PARALLEL to the roof panels.

i would recommend you adopt method 1. it's the most flexible and does not require identical panels.

 
« Last Edit: January 15, 2020, 12:37:27 PM by solarman »
KZ MXT20 480 W solar
ORV 24RKS 960 Watts solar
48V LFP, 2000W inverter/charger
Ram 2500 CTD

rbTN

  • ---
  • Posts: 113
Re: combining portable solar with roof mounted
« Reply #4 on: January 17, 2020, 02:33:27 PM »
thank you all, seems best to just have the portable be its on charging circuit in addition to the main panels.

it actually make more sense as well now that I think about the reason to use a portable in addition to the main, to catch the sun that I am not getting to the roof...
middle TN
was - 2001 Ram 2500 4x4 5.9 cummins, auto, camper pkg, trailer pkg (still have the 2001)
now - 2014 Ram 2500 6.7 Cummins, CC long bed SLT 4x4
2007 Thor Denahli 26RL
Equalizer hitch
300 watt Renogy system with 40amp mppt Rover