Plz Critique My 48V RV Solar Wiring Plans

Hey all,
I'm planning on DIY installing a 48V solar set up in my fifth wheel RV. I'm fairly new to solar, although I am quite comfortable working with household electricity. After doing a ton of research, I've put together my own wiring plans for my solar setup. I'm hoping someone out there more knowledgeable than my can take a look and point out if I'm missing anything, or I've there's anything I could do to improve the setup. Thanks!

10kwh storage and 6kw inverter capability is enough to power a small home, I'm just wondering what you're planning to power with it in an RV?

Attach the cables to the batteries in a diagonal method. Otherwise, the top battery does most of the work.

We generally recommend a switch downstream of the battery bank after the fuse. If your battery has a switch/breaker already then I don't see the need for the additional switch. We also recommend a Class T fuse immediately downstream of the battery bank.

The breaker between the PV and the solar charge controller has a label of 120v. Is that an AC breaker? If so, change that to a DC breaker.

How are you going to view the status of the system? The view that you get of the Cerbo GX through VictronConnect on your phone isn't a system status. For that you may want to add the Victron touch50 screen. To program the Multiplus you'll want to add either the Bluetooth dongle or the MK3 USB adapter.

Since you're isolating L1 and L2, maybe the regular Multiplus will work instead of the Multiplus II? I have yet to deal with a 50 amp RV system of my own but there are lots of 50 amp RV installs here on the forum that use a single Multiplus II.

What tool did you use to create the diagram? It looks great!

ShaneC said:

10kwh storage and 6kw inverter capability is enough to power a small home, I'm just wondering what you're planning to power with it in an RV?

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My rv is essentially a small home, ha. It is a 41 foot grand design momentum fifth wheel with 50amp power, and we will be full timing in it, so trying to size my power to match that.

I hope to be able to run the A/C for a few hours on really hot days, while still powering all of our daily use appliances. The reason I’m going with two 48/3000 multiplus II inverters instead of a single 120x2/12/3000 multiplus II is that 3000w split between both legs really doesn’t seem like enough to power the whole coach plus run an A/C unit

HRTKD said:

Attach the cables to the batteries in a diagonal method. Otherwise, the top battery does most of the work.

We generally recommend a switch downstream of the battery bank after the fuse. If your battery has a switch/breaker already then I don't see the need for the additional switch. We also recommend a Class T fuse immediately downstream of the battery bank.

The breaker between the PV and the solar charge controller has a label of 120v. Is that an AC breaker? If so, change that to a DC breaker.

How are you going to view the status of the system? The view that you get of the Cerbo GX through VictronConnect on your phone isn't a system status. For that you may want to add the Victron touch50 screen. To program the Multiplus you'll want to add either the Bluetooth dongle or the MK3 USB adapter.

Since you're isolating L1 and L2, maybe the regular Multiplus will work instead of the Multiplus II? I have yet to deal with a 50 amp RV system of my own but there are lots of 50 amp RV installs here on the forum that use a single Multiplus II.

What tool did you use to create the diagram? It looks great!

Click to expand...

Great point on the diagonal battery connections. I’ll update that now!

The batteries shown do have breakers already, so thinking that will eliminate the need for a downstream switch.

Regarding the batteries class T fuse… I posted this in a DIY Solar Facebook group as well, and they had pointed out that the lynx shunt has a built in fuse so I will likely not need the fuse in line with the battery positive cable at all. Can you confirm if that’s correct?

Thanks for the catch on the DC breaker on the PV as well.

Regarding the system status, I had hoped I would be able to view it in my phone with the victron connect and the cerbo. If there is no way this is possible than I guess I will have to install the victron touch screen as well.

As to why two multiplus instead of one, I replied with a more in-depth answer in my previous comment. But the short of it is. I think 3000w split between two legs won’t be enough capacity for us, and sadly they don’t make a multiplus 120x2 in any voltage higher than 12v, or in any wattage higher than 3000w.

I used Adobe Illustrator to make the diagram. It is a paid app, but I use it for work already. The app does have quite steep learning curve though, so would hesitate to recommend it for others looking to create just a wiring diagram

livingthefreeway said:

Regarding the batteries class T fuse… I posted this in a DIY Solar Facebook group as well, and they had pointed out that the lynx shunt has a built in fuse so I will likely not need the fuse in line with the battery positive cable at all. Can you confirm if that’s correct?

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The Class T fuse protects the cable. The fuse at the Lynx cannot protect the cable because it's at the wrong end.

If the Cerbo GX is connected to the Internet, you can use Victron VRM to make changes. My system didn't have Internet access at the time so I used the MK3 USB adapter. I now have Starlink but the Cerbo GX won't connect to it. I'm still trying to figure that one out. It may be an issue with the Cerbo GX. There's a fix that requires opening up the case, which I'm not ready to do yet.

HRTKD said:

The Class T fuse protects the cable. The fuse at the Lynx cannot protect the cable because it's at the wrong end.

If the Cerbo GX is connected to the Internet, you can use Victron VRM to make changes. My system didn't have Internet access at the time so I used the MK3 USB adapter. I now have Starlink but the Cerbo GX won't connect to it. I'm still trying to figure that one out. It may be an issue with the Cerbo GX. There's a fix that requires opening up the case, which I'm not ready to do yet.

Click to expand...

Thanks for that insight on the class T fuse! I’ll look into that. Unfortunately looks like the class T is hard to find and/or very expensive right now…