48V off-grid cabin system

[Spindoc73]

Hello everyone,

I'm planning a 48V solar system for an off-grid cabin that my kids and I have been building. We've just rough wired the house, and my question is what type of breaker box would simplify our life at this stage? We designed this place based on a gothic cathedral, and DIY'd the entire timber-frame project starting with the foundation. I camped for the last 3 years, and while this has been really insightful and fun, I'm ready to take a breather and read a book inside a well lit and insulated structure.

I would normally enjoy researching and trying to design a system over several months, but time is limited to 'power-on' in one month, so my first plan was to use an all-in-one inverter with a generator backup as well. From the inverter, is there a 'simplest' distribution box geared to this application that could save time and perhaps allow certain circuits to take priority, in case of backup power? Something that would simplify the wiring relative to a distribution box from a big-box store?

 

[MichaelK]

What I did was pick up an in-expensive electrical panel from HomeDepot.

Square D Homeline 100 Amp 6-Space 12-Circuit Outdoor Main Lug Load Center(HOM612L100RBCP) HOM612L100RBCP - The Home Depot

The Square D Homeline 100 Amp 6-Space 12-Circuit Outdoor fixed Main Lugs Load Center is UL listed for residential and commercial power distribution. This load center is built with a plated, aluminum bus

www.homedepot.com

The first thing you need to decide is whether you are going to have single-phase 120VAC, or split-phase 120/240VAC. What AiO are you getting, and what is it's output?

In my own case, I went split-phase, so I could power my 240VAC well-pump. With a standard North American electrical panel, each single breaker will be either L1 or L2 at 120VAC. Double-pole breakers will be L1 to L2 and produce 240VAC. My XW+6848 supplies that.

Keep in mind that many AiO inverters have no meaningful surge capability, so what 240V loads they can power will be limited. Anything running an electric motor at 240V might not start with an AiO.

I would study very hard your list of items to power BEFORE making your inverter purchase, so you aren't backpedeling after you find out stuff won't start. Research the surge capability of whatever you want BEFORE you buy. You can also determine the starting surges of anything you own with a clamp meter that can measure "inrush current".

 

[Spindoc73]

Good point - this will be a single phase 120V, though I'd like to have an option for split phase. I'm off grid electrically, but have a tap to water at the road. I have a well that feeds into a cistern and would rather separate from town completely, but I think that will have to be a project for someone else or a later time.

The MPP Solar LV6048 seems like a nice option to cover split phase, with 6 kW continuous and 12 kW surge?

 

[MichaelK]

Well, maybe the best strategy will be to buy a standard split-phase box, but only wire it for L1 with the first inverter. That way once the box is plastered into the wall and it looks nice, you won't have to rip it out later. Just make sure your conduit is wide enough to accomidate additional wires. Alternatively, just string three conductor wiring from the start and just leave the L2 wire disconnected. Make sure you label it though so that anyone coming along later will understand what it's for.

 

[12VoltInstalls]

best strategy will be to buy a standard split-phase box, but only wire it for L1 with the first inverter.

Last I saw there was a fairly inexpensive 100A 120/240 panel at Home Depot. Way too many breaker possibilities for 100A but that’s not really a downside as it’s not illegal or unsafe in any way.
That’s a good idea here because options are nice; 10 circuits is better than four or six for one leg of a little panel. And you don’t have to put a 100A breaker as a main, you can go smaller as needed.

 

[Bluedog225]

Not to hijack, but what does “6 space; 12 circuit” mean? I would have thought 6 spaces [for breakers] therefore 6 circuits. No?

I’m in the same boat…err….cabin….

 

[Rednecktek]

Not to hijack, but what does “6 space; 12 circuit” mean? I would have thought 6 spaces [for breakers] therefore 6 circuits. No?

I’m in the same boat…err….cabin….

There are 3 sizes of breakers commonly available, singles, doubles, and splits. A single breaker would take 1 "Space" and provide 1 "Circuit". A double breaker would be for 220v, take 2 "Space" and provide 1 "Circuit". There are split breakers that take 1 "Space" but have 2 breakers in there so provides 2 "Circuits". If you put 6 of the split breakers in the panel, you'd use 6 "Spaces" and get 12 "Circuits". No, you can't put a 220v split phase on a split breaker as a split breaker takes power off a single lug in the panel, not the two lugs that are out of phase.

This is a picture of a 12 space, 24 circuit panel that's mostly populated so you can see how each split breaker fits into a single breaker's space. You can see that there's a combination of split and double breakers.

 

[Bluedog225]

Got it. Thanks for the great response!

 

[Spindoc73]

I just went with a standard 200 amp 120/240 Siemens box. I was hoping for an 'intelligent' box where I could describe circuit priorities via algorithm/app, which I assume could still be done by filter the distribution box outputs. In any case, the 6048 has split phase outputs and a neutral, so it seems I can use just as a grid input to the box.