Need some help with designing my Skoolie system

[Surfsolar]

For background I build sprinter vans for a living. In the vans we use victron batteries, victron multi-plus 3k inverters, orion alternator charger, and Victron MPPT. The most solar we ever put on vans is 400watts. All systems we build are always 12v.

I've been watching will prowse for years and recently have been really interested in trying the EG4 server rack batteries. I just started my personal school bus conversion project and am trying to get together what I want the electrical system to be. I am close to just doing what we do in vans and keeping it simple to me, but the systems we put in vans are very expensive and pretty limited compared to well done RV systems using 24v or 48v. I also am on a budget of keeping it as low as possible without sacrificing the use of the system such as running 115v Roof A/C, possibly having a microwave, ect.

At this point my system would be 1 or 2 EG4 server rack batteries, probably around 800-1200 watts of solar, 3kw Inverter, and shore power hook up. I don't think I'll add alternator charging as of now just because I hope to be able to supply enough solar/have enough battery bank to not need it.

From all the videos I have watched about 12v vs 24v vs 48v, it seems 24v is the preferred for an off-grid camper/RV. I really like the idea of the all in one inverters by growatt and EG4 but those especially the EG4 only comes in 48v. I guess I'm just wanting some opinions on which of the latest tech is best for this scenario. Do you think I should just go 48v? or should I abandon the all in one idea and keep it separate with an inverter, and mppt It's not too much of a difference cost wise to either do All in one or separate.

 

[12VoltInstalls]

systems we put in vans are very expensive and pretty limited compared to well done RV systems using 24v or 48v

Here’s a thread with some entry level basics you probably already know.

In my opinion 24V is somewhat a waste of time anymore. 48V is reflecting the economy of scale that accompanies demand and commonality.
Unless the bus is 24V (native diesel starting system 24V offers only one advantage: smaller battery cables- and even then 12V or 48V make sense.
Assuming bus chassis is 12V from the oem, there’s lighting and other RV-esque benefits to doing a 12V system. That’s is up to 2500W inverters or maybe 3000W inverters.
But at that point 48V makes too much sense.

budget of keeping it as low as possible without sacrificing the use of the system such as running 115v Roof A/C, possibly having a microwave, ect.

3000W will do that; A/C plus microwave simultaneously could be an issue at times.

don't think I'll add alternator charging as of now just because I hope to be able to supply enough solar/have enough battery bank to not need it.

There’s simple inexpensive ways (relatively) of doing that; having the option could be nice at some point?

FWIW I have a “stationary rv” with a household fridge, coffeemaker, TV (that maybe turns on every three months) on a 3000W QZRELB inverter (big inverter let’s me run tablesaw, routers, welder, sanders, small compressor) so I think that is more demand than your rooftop (8-10A?) A/C unit. It fits fine. I also use an electric frying pan and on bright sunny winter days I run a 450W electric heater when the batteries are full.

All lighting, phone chargers, pump, fans, range hood, propane furnace are 12V.

It’s simple, inexpensive and works.

hope to be able to supply enough solar/have enough battery bank to not need it

I’m 100% offgrid. I charge with six 315W vertically mounted panels on the side of my woodworking shop. Takes up about 6’x20’ of space. I haven’t run the generator since the first week of December. I have plenty of power.

probably around 800-1200 watts of solar

2kW of solar like I have is going to make you a happier…. camper. Solar panels are cheap!

seems 24v is the preferred for an off-grid camper/RV

those are opinions. ‘Preferred’ probably because 3000W on 12V is a heckofalotta Amps and you halve thst with 24V.
But I wouldn’t do it.
FWIW a number of 48V AIO’s have a 12V output built in. I’ve considered that myself!
But I’d stay 12V or go 48V; 24V is mostly a unicorn except in the offshore cruiser segments and even they have a bunch of 12V thingies.

like the idea of the all in one inverters by growatt and EG4 but those especially the EG4 only comes in 48v. I guess I'm just wanting some opinions on which of the latest tech is best for this scenario. Do you think I should just go 48v? or should I abandon the all in one idea and keep it separate with an inverter, and mppt It's not too much of a difference cost wise to either do All in one or separate.

The growat lines bother my head in some aspects. I had read less snarl on MPP and now EG4; I’d stay in that environment. PowMR is another cheaper alternative that could work for you.

I use an MPP 1012LV-MK as a charge controller for four panels 2S2P, and a powMR 60A SCC for two panels 2S. The 1012 inverter is off, only there for backup.
I have ~5kW of batteries, and the 3000W Reliable-brand (QZRELB) inverter. That QZRELB inverter is like only 16W idle consumption…
I’d either buy three 60A cheapo mppt’s (like mine) and skip the AIO, or better: buy several smaller Victron SCC‘s and run the standalone component inverter; OR:
If you buy an AIO it has an onboard 80A utility charger built in if a generator or ‘shore power’ is ever going to be used.
This is how my 1012 works:
Inverter switch is off, SCC wakes up after dawn and charges (LiFePo) batteries and shuts down at sunset.
If I fire up the generator the ‘utility charger’ wakes up and chargers at 80A
No idle draw.
So think of my generator like shore power: you plug in, it charges batteries.

They do make a 3048 AIO fwiw but I personally would stay 12V because it’s simple, repair parts won’t be special order (every parts store or RV dealer has stuff to get you out of a jam).

Hope these thoughts and rambles are useful.