I'm buying a new NorthStar 850SC pop up truck camper. The dealer is installing a 170w panel on top, a 30a controller with 2 AGM batteries. Says he's done a lot of this install which is supposed to be the exact option that comes from the factory if ordered.I was thinking of having him install a outside plug for another 100w suitcase solar panel for those times when the camper is in the shade..Will I need to have a larger controller installed so I can run both panels, 270w total?? Or are there any flaws with my thinking????thanks

No, you'll be fine. Watts/voltage= amps. See my next post...

Suitcase solar is a pain...set up, take down. Install a second panel on the roof. The panels should match each other. 100 watt panels may fit easier. Regarding whether that controller is adequate, add the max number of amps all the panels can produce and match to 80% or so of the controller’s max. 400 solar watts is usually the max for a 30 amp controller. Do some reading.Two AMG batteries? For how much? Are they recently manufactured? What AH capacity?

Has the dealer revealed the wire sizes he/she plans to use? Run lengths? Panels to controller. Controller to batteries?

Your suitcase set would likely have its own controller, which you can have go to the battery separately from the roof set's controller. Or you can perhaps arrange to have the two arrays go to the one controller.The size of controller in amps rating is more important for a PWM controller, which heats up of you "over-panel" so more amps go to the controller than it is rated for. The heat will fry the controller.So the rule with PWM controllers is to have its amps rating be about 25% more than the "expected amps". How many amps is that? Use the Isc rating of the panel with PWM (not the lower Imp rating which only applies with MPPT controllers)A 170w panel could be a 12v or a 24v panel. If it is a 24v panel, you can't just add your 12v suitcase set to it, so that means having the two controllers in parallel onto the battery bank. No problem when the two controllers have similar high output voltage set points --14.6v say. They will add their amps.So the 30 amp controller with the 170w panel (even if it is an MPPT controller and the panel is a 12v)-- Isc if that is a 12v panel will be about 11.8 amps. Isc for a 100w panel is about 6.3 amps. So your expected amps with both on that one controller would be about 18.1 amps. So the 30 amper can handle that easily.And to repeat, if it is an MPPT controller on a 24v panel, you can't add the 100w 12v panel anyway. Another thing is with MPPT controllers, they have an amps cut -off so even if the array supplies more amps, the controller won't fry because it limits the amps to its rating.

BFL13 wrote:And to repeat, if it is an MPPT controller on a 24v panel, you can't add the 100w 12v panel anyway.Good point. Not in parallel. Series would work as each panel is rated around 8 amps, provided the controller could handle 36v.. BUT NOT when one panel is in the shade.

Solar on a Pop Up Truck Camper ? or 2 | Good Sam Community

11 Replies

BFL13
Explorer II
Mar 15, 2020
Looks like you can do lots of solar on the 850SC! :)

https://amsolar.com/solar-panels-for-rv/2018/4/17/4022018-2018-northstar-camper-850sc
2oldman
Explorer II
Mar 15, 2020
Dagwood_55 wrote:
I think I'll let Arizona Sun & Wind put together a system with the proper wire sizes, controller, breaker box/fuses and do it myself.
That's the best way to really understand what you have.
BFL13
Explorer II
Mar 15, 2020
The dealer might have been intending to use this kit, which uses a 12v 170w panel.

https://www.zampsolar.com/170watt

ISTR posts where the new RV has a built- in connector for wiring Zamp panels on the roof. Not sure. Also with that ISTR something about the connection needs to be reversed if using other brands. Not sure.

Might have been another brand--somebody here can confirm.

So even if the suitcase is 12v, there might be a trick to getting it connected, and you have to go to the battery with its controller in parallel with the roof's controller.

This 170w panel is a 24v that needs an MPPT controller.

https://www.invensun.com/solar-panels/170w-solar-panel

If you are starting over as mentioned, then you can now decide to go go with more wattage, single panel with MPPT, or stay with all 12v and PWM, or have one of each with the two controllers in parallel on the battery. Lots of choices!

Another way, since putting a roof panel on a pop-up seems like pushing things? is get two of those suitcases for 200w and no installation required.
steveh27
Explorer
Mar 15, 2020
You'll like adding a portable as you can then park in the shade and put the panel in the sun. Moving it around is easy and not a problem.
Dagwood_55
Explorer
Mar 15, 2020
I think I'll let Arizona Sun & Wind put together a system with the proper wire sizes, controller, breaker box/fuses and do it myself. I'm just not sure the dealer will install a good, matched system. Once I get it all nailed down, I'll post and get some review of what I'll hope to be doing
Thanks all
Dagwood_55
Explorer
Mar 14, 2020
Sounds like I need more info from my dealer/shop.
2oldman
Explorer II
Mar 14, 2020
BFL13 wrote:
And to repeat, if it is an MPPT controller on a 24v panel, you can't add the 100w 12v panel anyway.
Good point.

Not in parallel. Series would work as each panel is rated around 8 amps, provided the controller could handle 36v.. BUT NOT when one panel is in the shade.
BFL13
Explorer II
Mar 14, 2020
Your suitcase set would likely have its own controller, which you can have go to the battery separately from the roof set's controller. Or you can perhaps arrange to have the two arrays go to the one controller.

The size of controller in amps rating is more important for a PWM controller, which heats up of you "over-panel" so more amps go to the controller than it is rated for. The heat will fry the controller.

So the rule with PWM controllers is to have its amps rating be about 25% more than the "expected amps". How many amps is that? Use the Isc rating of the panel with PWM (not the lower Imp rating which only applies with MPPT controllers)

A 170w panel could be a 12v or a 24v panel. If it is a 24v panel, you can't just add your 12v suitcase set to it, so that means having the two controllers in parallel onto the battery bank. No problem when the two controllers have similar high output voltage set points --14.6v say. They will add their amps.

So the 30 amp controller with the 170w panel (even if it is an MPPT controller and the panel is a 12v)-- Isc if that is a 12v panel will be about 11.8 amps. Isc for a 100w panel is about 6.3 amps. So your expected amps with both on that one controller would be about 18.1 amps. So the 30 amper can handle that easily.

And to repeat, if it is an MPPT controller on a 24v panel, you can't add the 100w 12v panel anyway.

Another thing is with MPPT controllers, they have an amps cut -off so even if the array supplies more amps, the controller won't fry because it limits the amps to its rating.
Lwiddis
Explorer II
Mar 14, 2020
Has the dealer revealed the wire sizes he/she plans to use? Run lengths? Panels to controller. Controller to batteries?
Lwiddis
Explorer II
Mar 14, 2020
Suitcase solar is a pain...set up, take down. Install a second panel on the roof. The panels should match each other. 100 watt panels may fit easier. Regarding whether that controller is adequate, add the max number of amps all the panels can produce and match to 80% or so of the controller’s max. 400 solar watts is usually the max for a 30 amp controller. Do some reading.

Two AMG batteries? For how much? Are they recently manufactured? What AH capacity?