This is a draft drawing of my RV Solar / Charging system upgrade. 2022 Alliance 310RL (35ft 5th wheel) that came with the manufacture’s “Super Solar” option, which included 3- 320w Renogy PV panels mounted on the roof, 3 Renogy 100ah Lithium batteries, Renogy MPPT Solar charger, and a Renogy 60A DC-DC Converter. Cummins 5.5kw generator already onboard. Manufacture wiring is on the hideous side of craftsmanship, and I prefer Victron hardware over Renogy, so I decided to gut the system and start from scratch running a 24v system feeding a 24v/12v DC-DC 80A converter for the 12V DC loads.
I have not purchased an Inverter yet. Hoping that Victron comes out with a 4K/24V 2x120Vac in the near future.
Plan is to build a system that I can stay off grid for extended periods of time and recharge while traveling .
Items that I have already purchased:
2 Epoch V2 460 ah batteries
Victron MPPT 150/70
Victron Lynx Distributor
Victron cerbo GX w/ 5" GX Touch
Victron Battery Protect 100
Victron Smart Shunt 500
Switches / Fuse Holders.
Please feel free to scrutinize and provide feedback.
They just came out with a new 12/4000 120X2 Multiplus II.
Obviously there will be strong and mixed opinions about this but not everyone recommends 24V as the best option for a 12V system. The reasoning being, you have not only a continuous efficiency loss converting to 12V but now you have additional failure points including the terminals as well as the converter itself. I know very very smart and experienced Victron technicians that have abandoned their endorsement of 24V battery banks in 12V systems. Some of these techs have built and lived in multiple rigs they have built themselves utilizing 24V battery banks and have chosen to not do it anymore for the reasons I have listed.
Is this a 50A RV? We have a MP2x120 24V 300Ah system in our coach. The higher voltage doubles the amount of solar per MPPT. You might find it more economical to use several smaller MPPTs vs. one large device. We run four 75/15 & 425W panels.
I use a dumb Victron 70A 24/12 feeding a group 31 AGM buffer battery for house loads, it was before the XS-1400 came out. Our 12V loads are pretty minimal, fans & lights, but we do have a hydraulic pump for slides and levelers.
The GX displays are a bit too small for my old eyes. There is a Victron supported app for Android tablets, I have a 10" in a wall mount.
A 4kW would be nice to have. On occasion, the microwave has clashed with the coffee pot. 24V DC aircon works so much better than the Dometic hogs.
I don’t see any downside to 24V. Isolating the alternator from the lithium is a must, so adding another step of conversion to a lightly loaded 12V system isn’t much compared to doubling the inverter & solar current. The terminals and crimps have the same resistance at 24V as at 12V.
thanks for the feedback. Yes, 50a DC system. You definitely gave me things to consider, especially using an Android Tablet as a display as the 5" is really too small.
Onboard Generator is directly wired to existing Renogy 3K inverter that has an auto transfer switch between shore and Gen power. Inverter charges system batteries.
I am interested in learning more about how you remotely monitor your system when in storage, if you’re willing to share.
I see the Quattro 2x120 is a perfect unit for the job. My coach has a transfer switch, had that Quattro unit been available when I built, I think I would have went that route instead of the MP.
Sure it’s easy, the Cerbo sends everything to Victron’s VRM to monitor. For an internet source I use a GL-X3000 router as the local RV network. Internet can be from the WiFi repeater, cellular, or Ethernet (Starlink). A little 7 in 1 dome antenna on the roof handles everything (except Starlink).
I do have a handful of devices to shed load off the inverter when off shore power. I use Shelly relays over WiFi, and a TCP/IP I/O module for 12V stuff like the generator start/stop, dumb DC/DC enable, etc. I use Node-RED in the Cerbo to automate as much as I can. It’s a bit addictive.
Keep in mind that the 2x120 Multi and Quattro have only a 120 volt inverter that sits on the L1 leg. The L2 leg passes through when on 120/240 volt shore power (or generator). This also means is that there is no power assist on the L2 leg. When on 120 volt shore power or when no shore or generator power is available, the inverter feeds both L1 and L2 IN PHASE so 240 volt loads (if any) would not work.
Check to make sure your generator is a true 120/240 split phase unit. Some generators output two separate legs but they are in phase. In that case, the 2x120 Quattro would only utilize one leg from the generator, cutting its output in half.
Separate Quattros for each leg would be a better all-around solution or you could use Multis with a transfer switch ahead of their AC input.
The 70 A fuse at the input of the Orion is not needed as that line is protected at the power source (vehicle battery).
Are those fuses at the input and output of the 24 to 12 volt converter? Probably not needed. The input is protected by the fuse in the Lynx and the output will be current limited.
Choice of 12 or 24 volt DC depends a lot on wire distances. If batteries and inverter are close then you can probably simplify by using 12 volt battery bank and inverter. You would need a larger MPPT or as others mentioned use multiple MPPTs.
Thank you for the monitoring information. I appreciate the input as it would have taken me time to get a good monitoring system figured out. I do like Shelly devices as I have several Shelly Matter / Z-wave connected to my Homey Pro home automation system.
Thank you for looking over my design and providing feedback. Suggestions noted. Good information on the Inverter as I really haven’t selected or purchased an inverter just yet. Hoping Victron comes out with the 4K / 24v inverter with an ATS before I complete this build. On board Generator L1 and L2 are in-phase with each other. Thanks for reminding me to consider this in my Inverter selection consideration.
With the two legs of the generator in phase, no Victron solution will permit full 5.5 KW output from the generator. The 2x120 units will simply reject the L2 leg in this case. The same would be the case for separate inverters configured for split-phase operation.
If the generator can’t be rewired, a transformer in the L2 path from the generator could reverse the phase and provide a pair of inverters true split phase power. With a 2x120 unit, L2 would pass through and power your loads as I described with shore power.
I’ve heard you can double up the two generator phases onto L1. The limit would be the inverter transfer switch max AC current (50A?) or the genset neutral wiring.
I haven’t tried this yet on my MP 2x120 but it’s on my todo list.
