Building a mid size system

@Dave Angelini had it mostly right. Our cabin was wired for 110VAC when we built it 44+ years ago, but until 2017 we ran a generator when we needed power. The family made the decision to - at least for now - plan for no days of autonomy. So our battery bank was sized for no more than 50% DoD, but only for one day.  So far that has worked out fine, the only time we end up having to run the generator is if a larger number of people are there.  My wife and I and sometimes one of our two adult daughters can pretty easily get by without running the generator.

The cabin is mostly used only in the mid-spring to late-fall. Either my brother or my sister will probably go up in the next couple of weeks for the first time this year, and we usually close up the cabin for winter in November.

Also, the area where our cabin is gets a ton of cloudless days. In the summer we get periodic late afternoon thunderstorms, but it's not uncommon to go for a month or more with no rain at all. At 9,000 ft elevation, we get pretty high harvest from the panels.

As for what it is powering: Largest load is a 1/2 hp well pump, which runs for just under 3 minutes to fill the pressure tank. It may run 1-2 times for a shower, and maybe as many as 3-4 other times through the day. I budgeted 30 minutes of the pump running per day in that 3.3kWH.  We also allow for 30 minutes per day of some other larger load, like the microwave oven, blow dryer, or curling iron. Other than that the loads are relatively small: LED lights throughout the cabin, one ceiling fan, a cell phone booster, and plug-in chargers for phones and laptops.  The water heater, wall furnace, and refrigerator are all propane, run off what I think is a 500 gal tank that gets filled once per year.

As is said in countless threads here, the key is to carefully add up all the power for your loads (watts) as well as how long they will run (to give you the energy total, in watt hours).  Size your battery bank for that, accounting for DoD and days of autonomy, then build out the rest of the system allowing for the inefficiencies introduced by all the pieces.

Our parts list included 74 line items. It's funny, but at one point it looked like the system was going to cost around $6K, but all the little things really added up. $500 for concrete (ballast for our ground-mount), $300 for conduit and fittings, etc. I'm guessing I made 20 trips from our cabin to Home Depot, which was about a 3 hour round trip.