We just moved into our first offgrid house a little before Christmas, it took us 2 years to build it. We (the wife and I) did everything except the concrete flatwork and the sheetrock ourselves -- ditch digging, electrical, plumbing, roofing, everything. It's totally offgrid and completely code-compliant according to the inspectors. I can tell you about it, maybe something will "click".
We're a little above 10,000 feet elevation in the Colorado Rockies. The lowest temp I've seen here in 5 years is -15F. Usually during winter the temps range between 3F and 20F. The house is 375 square feet inside, basically a greatroom with a kitchen and bathroom.
Our foundation is a concrete slab. It was poured inside ICF's. Below the slab is 2" of styrofoam insulation. The water lines are about 4' below that and have another 2" of styrofoam on top of them.
EVERYTHING in the house that is electrical runs on 12vDC, with one exception that will soon be remedied (a heating device for our on-demand water heater). We have full 120v available inside when we want it, basically we use it to recharge cellphones and run a hairdryer occasionally, that's it.
The lights are 12vDC, using standard household fixtures and socket converters that let us use automotive bulbs. The water pumps are Shurflo RV pumps. The refrigerator is an Isotherm CR90. The on-demand hot water heater is a PrecisionTemp RV-500. Heat is supplied by an Empire DV-35 propane heater that is thermostatically controlled but requires no electricity, its pilot light heats a thermopile. We also have a Jotul F100 woodstove. Insulation is R19 in the walls, R38 in the ceiling. We went for a cathedral ceiling to make it feel roomier, and it does. During winter when the temp is in single digits outside and we fire up the woodstove, we have to open windows to keep from getting run out of the place, an inside temp of 80F+ is almost too easy to achieve and it's taken some practice to learn how to keep it reasonable.
There's a 12v control panel in the kitchen above the range hood inside a cabinet. On average the house runs at maybe 4amps. The 12vDC isn't really 12v, it's really 13.7v provided by a Samlex switch-mode DC converter attached to our 24v battery bank. So we're talking about an average power usage for the entire house of maybe 70 watts. When I run my laptop it's about 60 watts by itself but a lot of the time the house is drawing zero current.
About 12' from the house is the generator/power shed. It's about 6'x12' in size, the south half is the electrical room and the north half is the generator room. They are separated by a wall that I made as airtight as possible. The generator room has never yet been used for a generator, it's currently full of "stuff" we have no other place to store.
The electrical room contains a battery box made from a large plastic tub turned upside down and vented through the roof with 4' poly pipe. It has room for just 4 batteries, and I may replace it this summer to expand the battery bank. Currently the battery bank is 250AH. It's connected to a Xantrex DR2424 charger/inverter, a Samlex SDC-30 switch-mode voltage converter to provide 12v, an Outback MX-60 solar controller (currently acting as a costly voltmeter as I've no solar array yet), and a meter/switchbox for an AirBreeze wind turbine.
The power lines between shed and house run underground. There's also a 1" poly pipe that's there for possible future instrumentation inside the house.
I *should* have run a second line between the power shed and the back of the woodstove so I'd be able to conveniently run a line from some kind of heat-powered device, but I failed to do that.
Currently we charge the batteries from a gas-powered generator which runs a few hours a day. The wind turbine helps out but was never intended to do the full job, just add a bit during blizzard conditions.
If there's more I can tell you, ask.