Where does my solar wiring go to? 2019 30’ International

[dustent]

Hi - my 2019 30’ International came pre-wires with the three port solar plug box on the roof. Any idea where inside the wiring runs to? It looks like all the 12v stuff is behind the front lounge, how do I get to it without disassembling everything?

Thanks!

[daleyocum]

I don’t know on the 30’ but usually the pre-wire goes to the infamous “Rats Nest” of wires usually near the front of the trailer. In my 25’ FB Twin it was under one of the beds. Usually there is a hatch of some sort to get access to it. There will be a couple of 10ga wires in there with a “Solar” label on them. I seem to recall them being green and yellow but could be wrong.

[wulfraat]

I have the same trailer.

(2017 model but nothing major has changed)

You should find the solar leads under the front couch, at the bulkhead, where the positive and negative bus bars are. Ahhh... meet the rats nest!

You’ll need to get on your stomach and make your way under the couch with the storage door open to fish around.

It’s a fun journey to find them!

[dustent]

Thanks guys - I was able to find them, two 10gauge green and yellow wires under there. There is also a cat5 cable that’s labeled “solar panel”, any idea where that goes?

I’m assuming the connectors on top of the rig are Zamp connectors and will need to be reversed to work with non-Zamp panels. True?

[daleyocum]

Originally Posted by dustent

Thanks guys - I was able to find them, two 10gauge green and yellow wires under there. There is also a cat5 cable that’s labeled “solar panel”, any idea where that goes?

I’m assuming the connectors on top of the rig are Zamp connectors and will need to be reversed to work with non-Zamp panels. True?

The Cat5 cable goes to where Airsteam thinks you’d like to put the display for the solar charge controller. You can use it for whatever you like, of course. On my 25’ it goes to right under the battery status panel in the kitchen. You pull out that panel to see it.

[lewster]

Hi Dustent,

While you have successfully found the 10AWG cables present in your coach, we have found that this size of cable is woefully inadequate for any solar charging system over 200 watts (2 panels).

We have chosen (for over 15 years) to bypass the provided cables in favor of using far more robust cabling (400 watts = 6AWG, 700 watts = 4AWG, etc) which perform much better than the simple 10AWG cable found with your rig.

Please feel free to ask more about this at any time.

Thanks!

Originally Posted by dustent

Hi - my 2019 30’ International came pre-wires with the three port solar plug box on the roof. Any idea where inside the wiring runs to? It looks like all the 12v stuff is behind the front lounge, how do I get to it without disassembling everything?

Thanks!

[dustent]

Originally Posted by lewster

Hi Dustent,



While you have successfully found the 10AWG cables present in your coach, we have found that this size of cable is woefully inadequate for any solar charging system over 200 watts (2 panels).



We have chosen (for over 15 years) to bypass the provided cables in favor of using far more robust cabling (400 watts = 6AWG, 700 watts = 4AWG, etc) which perform much better than the simple 10AWG cable found with your rig.



Please feel free to ask more about this at any time.



Thanks!

Hey! So do you pull thicker gauge wire down the same path and use the existing connector box? Or do you just scrap it and start over? I’d like to get 6 x 100w panels up there if possible so this 10g wire isn’t going to cut it.

[steverino]

Dustent, I can tell you the route that AMSOLAR took to install 600 watts of panels on my 2018 Classic 30, which has identical floor plan to your Intl’:
Junction box was installed on roof above the wardrobe. 4 AWG cables from the junction box entered the wardrobe via a roof penetration, ran down the inside of the closet, and forward underneath the galley cabinets. Solar cutoff switch was installed in the wardrobe. Near the entry, floor was penetrated and cables ran forward to the existing floor penetration near the 12v junction rats nest under the front sofa. Solar controller was installed under the front sofa, curbside. Hope this helps.

[wulfraat]

Lew did my install (2017 30’ international).

4AWG wire from 8 100watt am solar panels - came down through the fridge vent. No drilling or roof penetrations. Left the factory wiring as it was.

All my equipment is under the rear bed (vs front sofa). This was my desire as we use the under-sofa area for storage.

[daleyocum]

Originally Posted by dustent

Hey! So do you pull thicker gauge wire down the same path and use the existing connector box? Or do you just scrap it and start over? I’d like to get 6 x 100w panels up there if possible so this 10g wire isn’t going to cut it.

To directly answer your question, no the current wires can’t be used to pull new heavier wires. They make too many twists and turns.

There are those on this forum that swear you can use the pre-wire as long as you are willing to go to a series/parallel arrangement. In your case you’d either use a 24v or 36v arrangement and let the MPPT solar controller step down the voltage as needed to charge your batteries. Lew and AMSolar generally prefer to run heavier wire down from the panels so you won’t get the losses from a partialy shaded panel.

You can follow AirMiles and his four panel series parallel arrangement here. You could start out with a series parallel arrangement and then go to heavier wire later if you want to try it.

Since most of our camping is in forests here in Oregon I went with straight parallel but if you plan on camping in places with lots of sun series/parallel might be all you need.

[AirMiles]

The factory prewire is perfectly efficient with two panels, but the panels do not have to be only 100 watts each. You could use two 170W panels for 340W. Many of us use four 100W panels wired in series/parallel, making the equivalent of two 200W panels.

Here is a thread documenting the performance of many of our solar installations, including posts about my 400 Watts of panels running on the factory prewire: http://www.airforums.com/forums/f448...ll-181608.html Attached is a photo documenting four 100 watt panels producing 403 watts of solar and 30.1 amps of battery charging over the factory prewire!

Could the factory prewire be used with 600 watts of panels wired series/parallel, making the equivalent of two 300 watt panels or three 200 watt panels?

[lewster]

Hi Dustent.

I normally pull wire thru the fridge cover, like Wulfraat indicated. From there, batteries, inverter and solar equipment can easily be placed either up front below your couch or behind under the bed (along with cables for you phone amplifier and anything else you need). All 6 of the solar panels easily go on your roof and get wired into the combiner box (new) that is placed in proximity to the fridge vent.

Thanks!


[/B]

Originally Posted by dustent

Hey! So do you pull thicker gauge wire down the same path and use the existing connector box? Or do you just scrap it and start over? I’d like to get 6 x 100w panels up there if possible so this 10g wire isn’t going to cut it.

[AirMiles]

Could the factory prewire be used with 600 watts of panels wired series/parallel, making the equivalent of two 300 watt panels or three 200 watt panels?

Short answer:
YES because the key is to do series/parallel groups of panels. 600 watts in three sets of two 100W panels would work great! By my calculation below in the "long answer" is that this configuration would be capable of producing 588 watts to the controller for a total loss of only 2.0%.

Long answer:
Doing six 100 watt panels on a 30' Airstream would require 54' of 10-2 on the roof. There would be three runs averaging 18' each at 34 volts with 6 amps. Using this calculator: https://www.calculator.net/voltage-d...es=6&x=52&y=21 the voltage at the rooftop box would be 33.78. Then we need to use the 30' of factory 10 AWG prewire to send 33.78V at 18 amps to the controller. At the controller we get 32.7V at 18 amps, or 588 watts using this calculator: https://www.calculator.net/voltage-d...s=18&x=80&y=19

Now let's redo the calculation using a full parallel design and 4AWG from the rooftop box to the controller:
We would need 96' of 10-2 on the roof. These runs would average 12’ in length running 17V at 6A using this calculator: https://www.calculator.net/voltage-d...es=6&x=60&y=18 the voltage at the rooftop box would be 16.86V. Then we need to use the 20' of 4 AWG to send 16.86V at 36 amps to the controller. At the controller we get 16.5V at 36 amps, or 594 watts using this calculator: https://www.calculator.net/voltage-d...s=36&x=61&y=17

Based on these calculations, a 600W system run over the factory prewire using three 200W series/parallel runs is nearly as efficient as running the system in full parallel with 4AWG to the controller. The higher voltage and lower amps of the series/parallel design is very efficient on 10 AWG.

[gator.bigfoot]

Nothing wrong with the series parallel approach as long as you can ensure your panels won't be shaded by roof vents, ac, antenna and trees. As soon as one panel is shaded you will loose a lot of efficiency with the others in that string. That approach works great in a fixed roof or tracker design but soon sees limitations with an RV.

If you're going to do it just bite the bullet and upgrade the wiring from the word go. Then you won't need to look back. You can always add additional panels or upgrade the electronics down the road, but changing the wiring is not something you want to do twice.

[wulfraat]

Originally Posted by gator.bigfoot

Nothing wrong with the series parallel approach as long as you can ensure your panels won't be shaded by roof vents, ac, antenna and trees. As soon as one panel is shaded you will loose a lot of efficiency with the others in that string. That approach works great in a fixed roof or tracker design but soon sees limitations with an RV.

If you're going to do it just bite the bullet and upgrade the wiring from the word go. Then you won't need to look back. You can always add additional panels or upgrade the electronics down the road, but changing the wiring is not something you want to do twice.

Agreed. I’ve done both on airstreams. Had parallel on my 25’. Moved to series when I added more panels. Then pack to parallel after unsatisfactory results due to partial panel shading at times.

On my current 30’ trailer we had a blank sheet - and went parallel with 4ga wiring. Very happy with the results.

[dustent]

Can someone expand on the shading issue? As I understand it the panels in series essentially act as a single panel circuit, but doesn’t sun = power regardless? Why would 2 100w panels in series take more of hit from shading than single 100w panels in parallel?

Thanks for all the comments too!

[SCOTTinNJ]

Originally Posted by dustent

Can someone expand on the shading issue? As I understand it the panels in series essentially act as a single panel circuit, but doesn’t sun = power regardless? Why would 2 100w panels in series take more of hit from shading than single 100w panels in parallel?

Thanks for all the comments too!

Very basic way to look at it.

In series if one panel is taking a big hit it knocks out both panels for 0% total capacity realization.

In parallel the same scenario will result in one panel still operating 100%, so you get 50% total capacity realization.

In practice ACs, vents, trees, clouds, etc OFTEN cast shadows on one panel but not another. At least partially.

[AirMiles]

Originally Posted by dustent

Can someone expand on the shading issue? As I understand it the panels in series essentially act as a single panel circuit, but doesn’t sun = power regardless? Why would 2 100w panels in series take more of hit from shading than single 100w panels in parallel?

Thanks for all the comments too!

A series pair of 100W panels is basically a single 200W panel. So if you get shade on one panel in the 200W series it will also affect the other 100W series connected panel. If you have one on each side of the AC and the sun is low in the sky causing shade on the one series pair panel, those two 100W panels will probably not be useful, but your other pairs of panels are not affected unless they are having the same shading issue. But if there's enough shade to knock out all three pairs of series-parallel panels, you probably would also knock out all 600W of parallel panels. But let's look at my real-world examples, not hypothetical situations.

I have four 100W panels that are on the four corners of my Airstream and have no shading issues from AC units. I have used my Airstream for over 100 days of boondocking in the past year (all documented in the Solar Show & Tell thread linked above). There were only five days where I had to boost charge my batteries with my generator. A couple of the days were dark, cloudy, rainy days with no sunshine. A parallel configuration would not have made the difference. A couple of the days were when I was under a full canopy of maple trees where it looked like dusk at noon. Again, a full parallel configuration would not have helped. There were many days where I had partial shading, but this never caused me to lack for charging. As long as one series pair caught some sunshine, my battery typically fully charged.

Again, there's over 100 days of boondocking documentation at these links:

10 days: http://www.airforums.com/forums/f448...ml#post2110788

30 days: http://www.airforums.com/forums/f448...ml#post2133206

20 days: http://www.airforums.com/forums/f448...ml#post2172254

30 days: http://www.airforums.com/forums/f448...ml#post2177241

Notice that my system achieved "float" status on all but a few days in the above linked 90 days. Shading is not a real-world issue for my series-parallel configuration.

[dustent]

In a setup of 6 panels I could run 2 pairs next to each other on each side (they should see similar shading across both panels) and the 3rd pair would have to be on opposite sides. That would minimize shading issues in this wiring configuration, correct?

My previous setup used 4 x 100w panels, I don’t recall the wiring but I’m pretty sure it was 2 series sets in parallel like we’re describing, and we only needed like an hour of full sun to fully recharge the pair of 6v Costco golf cart batteries. I get that shading might impact things but with 6 panels and 2 110ah batteries I think shading would have a minimal impact, no?

[AirMiles]

Originally Posted by dustent

In a setup of 6 panels I could run 2 pairs next to each other on each side (they should see similar shading across both panels) and the 3rd pair would have to be on opposite sides. That would minimize shading issues in this wiring configuration, correct?

My previous setup used 4 x 100w panels, I don’t recall the wiring but I’m pretty sure it was 2 series sets in parallel like we’re describing, and we only needed like an hour of full sun to fully recharge the pair of 6v Costco golf cart batteries. I get that shading might impact things but with 6 panels and 2 110ah batteries I think shading would have a minimal impact, no?

Looking a Wulfraat's layout and thinking about installing only 600 watts, I would install the six panels toward the front and not install the two panels at the rear. This would avoid the shading issues around the AC. Then I would wire the panels across from each other in a series as shown on my 400 watts. My research lead me to believe there is a benefit in having all the series aligned in the same orientation to the sun so that the MPPT can maximize the output on equal series. If you have two on one side as one series and two on the other side as a second series, they would have different orientations to the sun and would have different MPPT maximization points.

You want this /\ /\ /\ not this /\ // \\ - you want three series with equal orientations to the sun.