Side to side vs front to back arrays on coach?

[RipNC]

Installing 2 arrays each 3 panels in series. 3 panels on drivers side, 1 panel center and 2 panels passenger side. I have two options for dividing into 2 arrays:
Option A - 1 array of 3 drivers side panel and 1 array of center plus 2 passenger side
Option B - 1 array of 2 rearmost driver side plus 1 rearmost passenger side and 1 array of forward driver side, center and forward passenger side

Option A adds about 20' (round-trip) of wire (3 - 200w 24v nominal in series = +/- 114v 5.4 amp max).

I can rationalize either option. Thoughts and opinions welcome.

PS - all materials either here or enroute.

Thanks, Rip

 

[MisterSandals]

Its impossible for anybody reading this to know the shading circumstances. You do not want any of the 3 panels of a 3S array shaded as it will greatly diminish production of al 3 panels.

This will of course vary by the direction you park, whether the front vs back or drivers side vs passenger side are shaded.

Sounds like you have 2 MPPT inputs (1 for each array).

 

[RipNC]

Its impossible for anybody reading this to know the shading circumstances. You do not want any of the 3 panels of a 3S array shaded as it will greatly diminish production of al 3 panels.

This will of course vary by the direction you park, whether the front vs back or drivers side vs passenger side are shaded.

Sounds like you have 2 MPPT inputs (1 for each array).

2 Victron controllers. Yes, shading will vary at every stop, but I'm locating panels trying to avoid adjacent shade structures (really just the 2 AC units on the centerline) as much as possible. I was just curious if any one has done one method and wished they'd done otherwise etc...

 

[MisterSandals]

2 Victron controllers.

Which ones?
Battery voltage?

200w 24v nominal

Is nominal 24Voc or 24Vmp?

 

[0truck0]

I would go for the shortest wire option. 20 feet is a lot extra.
No way to predict the shade pattern.
I have two arrays, one at front, one at back, so predictive-wise this was smartest to at least have one in the sun if there is partial shade. Front to back is a bigger distance than side to side, thus more likely to be a shade/sun difference front to back.

What I would do different if I could start from scratch... Make the whole array on a frame that is on a hinge and can be tilted towards the sun. Tilting is significant and can reduce the number of panels you need to begin with.

 

[RipNC]

Which ones?
Battery voltage?

Is nominal 24Voc or 24Vmp?

150/45 Vmp is 37.2. 12v 400Ah LiFePO4 bank.

 

[RipNC]

I would go for the shortest wire option. 20 feet is a lot extra.
No way to predict the shade pattern.
I have two arrays, one at front, one at back, so predictive-wise this was smartest to at least have one in the sun if there is partial shade. Front to back is a bigger distance than side to side, thus more likely to be a shade/sun difference front to back.

What I would do different if I could start from scratch... Make the whole array on a frame that is on a hinge and can be tilted towards the sun. Tilting is significant and can reduce the number of panels you need to begin with.

Was out in the shop an hour ago putting together 6 sets of tilt brackets which I'm attaching to aluminum b strut (once my Zoro order gets straightened out). Nice to get your perspective on f/b arrays - that has been my thinking as it keeps the wires shorter. But then... with door side to the east in an open spot the 3 on passenger side would start producing early with driver side bringing up the rear in the afternoon. I'm getting a brain rash sitting on this fence (at least that's where my father used to say my brain was). Hmmm f/b would be a cleaner looking roof...

 

[MisterSandals]

150/45 Vmp is 37.2. 12v 400Ah LiFePO4 bank.

Thats a nicely matched kit.

You have another option to make 3 zones if that helps with wiring or shading:
2S2P into one SCC and 2S into the other.

 

[RipNC]

Thats a nicely matched kit.

You have another option to make 3 zones if that helps with wiring or shading:
2S2P into one SCC and 2S into the other.

Good point, will keep that in mind!
Last project I did was our boat and only one shade producer so 2 arrays of 2 panels each side worked. Depending on anchor swing could only shade 1 panel at a time, the rv poses more variables.

 

[0truck0]

I just posted this story. lol. 3 pairs of 100 watt panels going thru 3 charge controllers to two separate batteies. One set of panels can be switched to either battery bank.
My solution was to just add more panels so I still get enough power in the partial shade (is never really 100% shaded in the trees unless you are in a garage)