1 panel or 3 ?

[MrNatural22]

Looking for advise on which would be a better option for a cargo trailer conversion I’m slowly building.
the trailer is a 6’x10’ v nose so roof area is limited because of a roof vent in the center. The current plan was 3 100w panels in series—60v 5-6 amps into an MPPT for efficiency. They weigh approx. 65lbs together with an aluminum frame I built 65” x 47”.
I’ve found at santan solar a 327w 57v 5.7amp used mono high efficiency Sun power panel weighs 41 lbs. 61” x 41”.
Mounting one big panel is easier than mounting and securing the three together (VHB tape method w/safety tethers)
Is it better and more efficient to use the 3-100w or go with 1-327w with basically the same output ratings?

I had the three originally mounted on another bigger trailer build on the side and swinging up for use. That’s why the conjoined panel set up.

 

[gnubie]

If they are both paper rated (STCs etc) and are close dimensions to not cause any problems there's no efficiency issue.

With one big panel you might find there are heavier shading issues since shade falling across the panels. This comes down to exactly how the cells are arranged in the panel but you might find that shading in a particular way on the 300w panel knocks a 3rd off its production, while the same position shading on the 3 separate panels only takes out part of the production of one panel.

One thing to consider though is what happens if a rock smashes the glass while you are on the road. Shattering the glass won't necessarily kill the panel. Most cells are in fully encapsulated sheets but some are actually stuck on the glass and they will suffer badly from the glass being damaged. Even panels where the cells are fully encapsulated will take a performance hit when the glass is shattered, maybe 10%.

The glass actually forms a structural part of the panel. If it's shattered the panel will become quite wiggly and floppy. The smaller panels have more frame over all than the single big one. If their frames are joined together they'd be a lot more stable if one is broken.

Someone might pop up and word all this more nicely and understandably than I've stated it

 

[Rider]

I've found those roof vents really don't do much. They are small, and air doesn't move thru them unless you're moving, but when you're moving, you close it. Do you really need it?

Remove the vent, or mount the panels over it.

 

[MrNatural22]

If they are both paper rated (STCs etc) and are close dimensions to not cause any problems there's no efficiency issue.

With one big panel you might find there are heavier shading issues since shade falling across the panels. This comes down to exactly how the cells are arranged in the panel but you might find that shading in a particular way on the 300w panel knocks a 3rd off its production, while the same position shading on the 3 separate panels only takes out part of the production of one panel.

One thing to consider though is what happens if a rock smashes the glass while you are on the road. Shattering the glass won't necessarily kill the panel. Most cells are in fully encapsulated sheets but some are actually stuck on the glass and they will suffer badly from the glass being damaged. Even panels where the cells are fully encapsulated will take a performance hit when the glass is shattered, maybe 10%.

The glass actually forms a structural part of the panel. If it's shattered the panel will become quite wiggly and floppy. The smaller panels have more frame over all than the single big one. If their frames are joined together they'd be a lot more stable if one is broken.

Someone might pop up and word all this more nicely and understandably than I've stated it

Thanks I understand clearly what you explained no problem. And as long as performance is comparable I’m thinking maybe the one 327w panel would be an easier install. The price is great and as for shipping costs I’m close enough to the Phoenix area to drive up and pick maybe 2 of them up myself. (Spare for those oops moments you spoke of)Little cheaper also if picked up.

 

[MrNatural22]

I've found those roof vents really don't do much. They are small, and air doesn't move thru them unless you're moving, but when you're moving, you close it. Do you really need it?

Remove the vent, or mount the panels over it.

I have a fantastic fan installed for the vent and it they work great when parked for in or out airflow. If not for that I would definitely remove the vent for room. I have 74” across and 58” forward of the vent before the Vnose.
I’m trying to keep everything as close to the CC for a short run of cable (basically straight down) into CC. The electric panel, battery and simple plumbing are all mounted in cabinets I built into the V portion. (Caution Construction Zone?)