Off Grid Cabin Go 12DC and 120AC or all 120AC

[aspen12777]

We are in the middle of a complete remodel of our off grid cabin. It has been taken down to the studs. This brought up an idea. I see that I have two pretty good options. There are four buildings that would need to be connect main cabin, bunkhouse, utility shed and Tikki bar.

1) Wire the cabin and outbuildings with traditional AC wiring and distribution, stay with our propane fridge and put in a 24V or 48V inverter/battery systems. This is what other cabins in the area have done to replace their gensets.

2) Wire the cabin and out buildings like an RV, some DC and some AC. It seems that it would make the most amount of sense to go with as 12V system. This would allow me to run a Fridge, lights, and water pump on DC. This seems to make a lot of sense to me and I feel that it would be more efficient and most of the time I could just have the inverter off. I would only turn the inverter on when cooking, watching TV, running power tools or the vacuum. Most devices the family uses charge off USB(Iphones, tablets, speakers....) so this makes to charge this off DC, as we currently just charge them in the truck. I would need to double up on the wiring but not that much as the DC would be for lighting, the fridge and USB charging, then I would wire up AC plugs as normal in the rooms and kitchen.

Before the remodel we just had a Genset so we only had power when we wanted it bad enough to put up with the noise. I am not trying to keep the cost down, but I am limited on places to put panels and the amount of sun I will get because of trees.

I am leaning toward option 2, but I wanted to see if I am missing something.

Thanks for you feed back

 

[timselectric]

A lot of tv's use 12vdc, now. They just have a 120vac adapter. Dc in the main cabin is efficient. Probably not, for the out buildings. Unless you keep the load very low, to avoid large wiring.

 

[aspen12777]

I also like option 2 because it seems more reliable for the most important items I need, keeping my food cold and the lights on. As long as I have 2 Solar charge controllers and 2 batteries, I should be good. I figure my DC loads needed in the the outbuildings would be low, well under 10A as its just for lighting.

 

[timselectric]

Should be a very reliable setup. And easy enough to add more batteries, if needed in the future.

 

[John Frum]

How far apart are the buildings?
Voltage drop over distance is brutal at 12 volts.

 

[aspen12777]

If I locate the system in the central building the runs will be between 50 to 100 feet, which would put me at 8 gauge if I could live with 5% drop, which I think would be OK for lights to a bunkhouse or shed. That would be at 10A, which is a lot of lights, more than likely it would be closer to 5A.

 

[John Frum]

If I locate the system in the central building the runs will be between 50 to 100 feet, which would put me at 8 gauge if I could live with 5% drop, which I think would be OK for lights to a bunkhouse or shed. That would be at 10A, which is a lot of lights, more than likely it would be closer to 5A.

I make it 10.78% drop over 200 feet round trip for 10 amps at 8 awg.

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[timselectric]

I'm getting 12.24% drop at 10 amps.
6.12% at 5 amps.

 

[aspen12777]

I forgot to account for the round trip….. More to think about. I only need 4 LEDs in the outbuildings, that’s what is there now. That’s under 40W, 3 to 4 amps.

 

[Bluedog225]

I’m putting in two small DC systems to avoid running wires. A couple of panels, a small mppt, a 100 ah battery. Done.

 

[timselectric]

That's a better option.

 

[Wellbuilt]

I would just go with a 48v system and run every thing on AC then there is nothing to think about ? Add a few extra panels

 

[MichaelK]

My choice was going with 48V, and sticking with standard AC only. Couldn't be happier. One thing to consider is the AC only is going to be more energy expensive, but what I've found is the it's so cheap to add additional solar now, there's really no reason anymore to stick with 12V. I think it made more sense when solar was 4$/W. Today it's 4W/$.

 

[John Frum]

Will the outbuilding's occupants need ventilation fans?
How about charging for personal electronics?

 

[timselectric]

I'm assuming that if more than a little lighting is required, the inverter is going to be turned on.
I could be wrong.

 

[aspen12777]

Will the outbuilding's occupants need ventilation fans?
How about charging for personal electronics?

USB chargers for cell phones would be nice, in the bunkhouse. The cabin is at 6400 feet, for ventilation we just open a window.

When I really think I about it I was trying to get a setup were lights would always be available and always work. I think I should upsize the solar and simplify the design.

 

[John Frum]

The cabin is at 6400 feet, for ventilation we just open a window.

Your cabin is larger than the typical McMansion?

 

[MichaelK]

Your cabin is larger than the typical McMansion?

I think he meant the altitude is 6400 feet.

 

[aspen12777]

Your cabin is larger than the typical McMansion?

6400 in elevation, in the Sierra Nevadas. The main cabin is about 1000 square feet, the bunkhouse in 250 square feet, the shed and the bar are around 100 square feet each.

 

[Wellbuilt]

What I can do is run my inverter in stand by .
It uses a lot less power over nite .
On stand by my led night lites blink so we can see to go to the bath room or what ever .
When the frig or freezers calls for power the inverter powers the house until they turn off
I have one 60w light bulb in the hall with a switch up stairs and down stairs that we can turn on to get power in a emergency .
I use 6% of my battery over nite on stand by from dark to day lite .
And 10 to15% if I leave the inverter on .
You could allways have a few lites run from a 48v to 12v converter but the converter uses some power allso