Outfitting ORV 280RKS with Solar

[RV Steve]

This is my first post here. I have been reading others posts for a couple months. I am a full time RV'R since 2015 and purchased my second trailer, a used 2021 Outdoors RV 280RKS, May 2023. My first trailer had 3 x 100 watt Renogy monocrystalline panels with a Schneider (Xantrex) C40 controller. I have been at an RV park in Fairplay CO since purchasing my second trailer which has bought me time to put together a nice solar system. As I've seen good deals I've purchased some components. I have 12 x 100 watt monocrystalline Renogy panels with tilt mounts; my roof is curved so putting these up will require improvising. I bought 2 Victron Smart Solar 150/60 TR controllers and a Smart Shunt. I need to purchase a Victron 12/3,000/120 MultiPlus, maybe a Smart Dongle, LiFePO4 batteries (4x Redodo 200AH Plus), wiring, fusing, and get started installing. My trailer has a Zamp ZS-3B three SAE port roof cap installed with 8 gauge wiring to the overhead front bedroom cabinet (factory assumed controller location) and 8 gauge wire from there to the front triangle battery location. The roof cap combines all 3 SAE ports in parallel and is limited to 30 Amps total (20 amps max at any SAE port) and 300 Volts.

1. I would like to wire my panels in two groups of six in 2S3P down each side of my trailer. This would put me just over the amperage limit of my roof cap. My panels are 24.3 volts Voc and 5.21 amps Isc. Taking into account temperature coefficient the Isc would be 5.34025 at -13 degrees Fahrenheit; in Colorado at 10,000 feet; it could happen during the winter. Wiring 2S3P would give me 16.02075 amps through 2 of the 3 SAE ports for a total of 32.0415 amps just over the 30 amp limit. Is that enough over to be a problem? I called Zamp and was told the SAE ports are wired together using short pieces of 10 gauge wire (3"or less) and then connect to 8 gauge wire that goes to the controller. They didn't employ a busbar to combine the 3 SAE ports in this model roof port but did in later models. They thought that at 32 amps I could experience a little voltage loss but no safety issues.

2. I am planning on using MC4 branch connectors to connect the series panels in parallel. Is there any reason why that wouldn't work? Is it better to run wire from each series connected set of panels to a busbar in a combiner box? Seems to me this would just use more wire.

3. Can I feed two charge controllers from my existing roof port which has one 8 gauge output? I was thinking of running the 8 gauge wire from the roof port to power posts where I could hook up feeds to each of the controllers. Or should I remove the existing roof cap and replace it with a combiner box like the one AM Solar makes?

4. I was looking at the service manual for the MultiPlus 12/3,000/120 and it recommends two 1/0 gauge positive and negative connections to the battery bank. Is there any reason why one 4/0 gauge connection wouldn't work? The latter would be simpler for fusing. FYI my trailer has a 30 Amp 120 volt AC electrical system.

Thanks in advance for your advice and input!

 

[sunshine_eggo]

I have 12 x 100 watt monocrystalline Renogy panels with tilt mounts; my roof is curved so putting these up will require improvising. I bought 2 Victron Smart Solar 150/60 TR controllers and a Smart Shunt.

Good choice. BUT why so much? You don't need anything near 150Voc, and 60A is well over what you need.

2X 100/50 would be notably cheaper and still meet all your needs.

I need to purchase a Victron 12/3,000/120 MultiPlus

Good choice.

maybe a Smart Dongle,

This only allows monitoring, not changing any settings.

1. I would like to wire my panels in two groups of six in 2S3P down each side of my trailer. This would put me just over the amperage limit of my roof cap. My panels are 24.3 volts Voc and 5.21 amps Isc. Taking into account temperature coefficient the Isc would be 5.34025 at -13 degrees Fahrenheit; in Colorado at 10,000 feet; it could happen during the winter. Wiring 2S3P would give me 16.02075 amps through 2 of the 3 SAE ports for a total of 32.0415 amps just over the 30 amp limit. Is that enough over to be a problem? I called Zamp and was told the SAE ports are wired together using short pieces of 10 gauge wire (3"or less) and then connect to 8 gauge wire that goes to the controller. They didn't employ a busbar to combine the 3 SAE ports in this model roof port but did in later models. They thought that at 32 amps I could experience a little voltage loss but no safety issues.

Why not 3S2P and avoid the current issue completely? At higher elevations, the thinner air means you may actually see > 1000W/m^2, and get even more current than you calculated?

2. I am planning on using MC4 branch connectors to connect the series panels in parallel. Is there any reason why that wouldn't work? Is it better to run wire from each series connected set of panels to a busbar in a combiner box? Seems to me this would just use more wire.

Branch are fine except MC4 is limited to 30A, so do not exceed. If you have more than 2 strings in parallel, each string needs a fuse/breaker. Easiest thing is to wire in a single MC4 fuse for each string.

3. Can I feed two charge controllers from my existing roof port which has one 8 gauge output? I was thinking of running the 8 gauge wire from the roof port to power posts where I could hook up feeds to each of the controllers. Or should I remove the existing roof cap and replace it with a combiner box like the one AM Solar makes?

You may not connect two MPPT to the same array. Period. They will fight each other over the array, and you will never get anything near optimum output.

4. I was looking at the service manual for the MultiPlus 12/3,000/120 and it recommends two 1/0 gauge positive and negative connections to the battery bank. Is there any reason why one 4/0 gauge connection wouldn't work? The latter would be simpler for fusing. FYI my trailer has a 30 Amp 120 volt AC electrical system.

4/0 may not physically fit.

 

[corn18]

4. I was looking at the service manual for the MultiPlus 12/3,000/120 and it recommends two 1/0 gauge positive and negative connections to the battery bank. Is there any reason why one 4/0 gauge connection wouldn't work? The latter would be simpler for fusing. FYI my trailer has a 30 Amp 120 volt AC electrical system.

I just used 4/0 for the positive and negative to the Lynx/batteries. The 4/0 cable ends are about the size of a Volkswagon so make sure they will fit. They fit on my MPII 12/3000/70 2x120. They tell you to run a chassis ground of the same size as the battery feed cables but the chassis ground stud will only accept a 2/0 ring terminal. So that's what I used.

 

[G00SE]

Nothing useful to add, but those ORV trailers are absolute tanks! The Northwood folks that started up in Oregon really know how to build an RV

 

[RV Steve]

Good choice. BUT why so much? You don't need anything near 150Voc, and 60A is well over what you need.

2X 100/50 would be notably cheaper and still meet all your needs.



Good choice.



This only allows monitoring, not changing any settings.



Why not 3S2P and avoid the current issue completely? At higher elevations, the thinner air means you may actually see > 1000W/m^2, and get even more current than you calculated?



Branch are fine except MC4 is limited to 30A, so do not exceed. If you have more than 2 strings in parallel, each string needs a fuse/breaker. Easiest thing is to wire in a single MC4 fuse for each string.



You may not connect two MPPT to the same array. Period. They will fight each other over the array, and you will never get anything near optimum output.



4/0 may not physically fit.

Thanks for your reply all your points are appreciated. I went with the 150/60 after crunching the numbers. On a cold sunny day at high altitude it's possible I could get around 110 amps. I don't want to waste any charging capacity so I went with two 150/60 controllers. Since I can't run both controllers off of one array I will have to replace the existing roof port. That leaves 2S3P in two separate arrays as my best option to guard against shading impact. I'm leaning towards using two small roof ports that can handle two cables each or using two duplex cables in one of those caps. Best options I found were inexpensive on AMZN.

I searched on the Victron Community website regarding the double 1/0 vs single 4/0 battery bank hook up and a Victron moderator said it's OK. The MultiPlus 12/3000/120 has two M8 bolts for each positive and negative connection.

 

[RV Steve]

Nothing useful to add, but those ORV trailers are absolute tanks! The Northwood folks that started up in Oregon really know how to build an RV

The ORV 280RKS is heavy at 8,690 dry and 11,000 GVWR. The Nash 23D was 5,000 dry and 7,000 GVWR. My 1997 F250 has to work hard to pull all of that weight in the mountains!