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Old 01-23-2023, 01:45 PM   #1
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Is there an optimal panel string layout?

Looking at getting a new 37ft 5th wheel and putting 1400-2000W on the roof. Probably two strings on independent SCCs, each probably series-parallel.

My question is, anyone think driver-passenger arrangement is better than a front-rear setup for the strings? Maybe it's a wash as I can't really think of why it would matter if the arrays are the same size

Just as an example so don't mind the odd number of panels in the groups, but is red or green better? Or it only matters based on where the shade comes from? I don't think the panel angles closer to the nose will cause too much variation in output
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Old 01-23-2023, 02:15 PM   #2
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I think it matters where the shade comes from
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Old 01-23-2023, 05:21 PM   #3
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I think it matters where the shade comes from
for sure but i am trying to determine if there is some other "logic" to apply such as probability of tree cover/shade at a site at a campground being less at the front of the space than the rear, which would make the red option better. Or are there other common situations that would have a slight improvement in output.

admittedly this is more of a thought exercise than anything
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Old 01-23-2023, 07:00 PM   #4
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location of AC units would be helpfull. Honestly I have 1920 watt on our roof and rarely see over 1300 watt unless its noon time and mid summer. Panels that are flat just dont produce what there rating. During winter I am luck to see 300 watts for 3 ~4 hours .
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Old 01-23-2023, 11:30 PM   #5
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location of AC units would be helpfull. Honestly I have 1920 watt on our roof and rarely see over 1300 watt unless its noon time and mid summer. Panels that are flat just dont produce what there rating. During winter I am luck to see 300 watts for 3 ~4 hours .
And all other things on the roof. Antennas, vents, fans, etc.
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Old 01-24-2023, 05:02 AM   #6
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I have eight panels on a 43' roof, and 3 A/Cs - 2 roof vents, 2 tank vents, sat antenna, etc. It's walkable but tight. Some placement thoughts:
- May be impacted by where you penetrate the roof to bring wiring in
- Putting 2 junction boxes to separate controllers will give you redundancy, manage loads, reduce long wire runs, and possibly keep all/most wiring under the panels
- It's worth getting raised mounts (to keep panels cooler) and allow tilting with add-on bars (AM Solar has a system that works well - significant power gains when boon docking longer periods)
- There are some 'slide-out' mounts for panels (2 panels stacked - one slides out over the side of the RV when parked)
- Recommend wire looms to cover exposed lines - in 5 years the sun did a fair bit of damage to wire sheathing
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Old 01-24-2023, 07:24 AM   #7
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I have 6 - 200w panels on our 35 ft 5er. With how they are laid out, I still have room for another 2-3 panels. As long as you plan ahead (which you are), I doubt you’ll have trouble fitting them.
Before researching panels, I’d start by making a very detailed map of your roof, locating the ac units, vents, etc. Odds are your trusses are 16” on center. You’ll want to make sure to locate panel brackets to hit those. Keep in mind you’ll need to clean the panels, so you might want to leave some space for a narrow walkway to navigate around the roof. Best of luck!
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Old 01-26-2023, 07:30 PM   #8
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Quote:
Originally Posted by TravelSolo View Post
Looking at getting a new 37ft 5th wheel and putting 1400-2000W on the roof. Probably two strings on independent SCCs, each probably series-parallel.

My question is, anyone think driver-passenger arrangement is better than a front-rear setup for the strings? Maybe it's a wash as I can't really think of why it would matter if the arrays are the same size

Just as an example so don't mind the odd number of panels in the groups, but is red or green better? Or it only matters based on where the shade comes from? I don't think the panel angles closer to the nose will cause too much variation in output
Is your plan to only have two parallel strings? If you have 10 panels as in your sketch, why not 5 strings of 2 series panels each? As you are probably aware, more parallel strings gives you more “shade resilience” at the cost of heavier duty wiring and more line losses. It’s all a trade-off, there’s no single correct answer.

On my last trailer, I had 6 x100w panels on three strings feeding a single MPPT controller. With 300Ah of LFP batteries, I never had to plug in unless I wanted Air Conditioning.
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Old 01-31-2023, 07:44 PM   #9
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I think drive-passenger is a better setup because a bit angled and one side would get better light than the other at times so output will be better. This only matters if they're on different controllers.

I have 3000w of solar in groups of 5 100w panels but only have 1 controller. I did 3 groups on each side
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Old 02-01-2023, 12:28 PM   #10
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Two types of shade you'll encounter, one is shading by what's on your roof, and the other is shading from the environment. The first you have more control over, so work with that one first.

We've been full timing for almost three years now and have camped in a lot of different places, from wide open desert, to completely treed over, and everything in between. My original system had panels on one side, and when we planned our boondocking or camping without power, we'd Google Earth the campgrounds to select the best sites if possible. Now, with panels on both sides, it doesn't matter nearly as much.

I do have an on board generator and a small portable, as backups so I'm good in any conditions.

In the winter, tilt brackets make a significant difference. I have 6 panels in 2s3p configuration with a single controller, and it's worked well.

Unless you camp in the same places, your local environment will vary a lot. If you plan ahead, and use Google Maps satellite view, you can have some control.

I did my own system and decided to use tilt brackets. While I've only used them a handful of times, they are always there should I need.

So, I'm in the group that says do what's best for your physical set-up. You have much less control over your environment so that much less of a factor.
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