diy solar

diy solar

Combining fixed and portable panels

elblueduck

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Joined
Sep 16, 2021
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7
I posted this over under panels as well not sure if here would be more or less appropriate.

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 up top next to tent. 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: https://richsolar.com/collections/rigid-solar-panels/products/100-watt-solar-panel
  • 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: https://richsolar.com/products/100-watt-portable-solar-panel-briefcase
  • 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.
 
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.
Need to do a power audit to figure your requirements. With the power audit, you gotta figure where you’re camping. There’s a link in my signature block that shows how once a requirement is established, Someone who live in gloomy cloudy Seattle requires multiple the panels and battery storage I do in sunny Arizona.
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?
Depemding on the SCC you got, you could probably put both of these in parallel. That could be a good way to start. That way if you need more portable panels, you can run an SCC for those.
haven't picked a charge controller yet so if yall have any recommendations that would be appreciated.
I’m a big fan of Victron SCCs, and if you go to there website they have a program to help you choose one write for you.
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I have three SCCs. Two for two different roof mounted arrays, and one for a ground mounted array.
 
Need to do a power audit to figure your requirements. With the power audit, you gotta figure where you’re camping. There’s a link in my signature block that shows how once a requirement is established, Someone who live in gloomy cloudy Seattle requires multiple the panels and battery storage I do in sunny Arizona.

Depemding on the SCC you got, you could probably put both of these in parallel. That could be a good way to start. That way if you need more portable panels, you can run an SCC for those.

I’m a big fan of Victron SCCs, and if you go to there website they have a program to help you choose one write for you.
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I have three SCCs. Two for two different roof mounted arrays, and one for a ground mounted array.
Thanks for the response. I honestly think I have a huge battery compared to what I will need. The fridge I have doesn't seem need a ton of power, like 1.5 amp per hour. Most of the time I will be taking 3 or 4 day weekends so I think the battery without any solar should be able to handle that with room to spare unless I'm misunderstanding something.

I do wonder if having them be at a small enough tilt so that I could fit 2 of them up there will really reflect in much loss at all. I havent drawn it out yet but I really only need to pick up about 2 inches, could even have it just hang of the back some.

I guess I could always try it just with the one controller and roof panels, just set up some tests in my ars with the fridge plugged in and see what the battery does. My backyard has very little shade so that would be in ideal charging settings. Then I could add the suitcase style panels if needed, and of those don't like running with the roof panels I can add a second controller. That would be the most expensive route if I have to buy the second controller but it would have all the panels running at the top of their band.
 
ZI think you have a sound plan.

I do think most of us do the “Put as much power as you can fit on the roof and hope for the best.”

Before we put the panels on and do the install goes up, we have a good idea of how muchg we need.

I had a couple of surprises. Biggest one was my hugest loss was to the DC Propane Blower motor. 9 amps when on. I’d already decided on four 6 volt batteries, totaling 220 ah usable, so I still had plenty of power left over in the day On my worst coldest day. If I don’t use heat, I could go weeks without recharging. I can last one cold night with the blower running all night. The second surprise was just good and was how little energy I tended to use Except for those cold days.

My biggest do over on the build would be to organize the roof panels a bit better and not put tilt mounts. The tilt mounts take an hour to put up and take down, and its just easier to use the portable panels when I need the extra 40% that tilting the panels can bring in the winter. For placement, instead of 600 watts on one side, I could have fit 900 to 1200 watts with better planning. I have plenty of power as it is now, it will always bug me though that it’s not at max efficiency.

THey’ll be things like that, but its all things to just work around and adjust.
 
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