New 8.5KW System

Welcome  to Bob the mayor...

First look at my sig line(s) that is the starting point for our OG house.. We estimated (calculated) use at ~ 3.5Kwh per day. Used CFL for all lighting, and all phantom loads minimized, we use wood heat, so no furnace or HVAC.  3 days autonomy included. We are due N of SEA about 300 miles and in the interior, so we would have similar weather to you and this year we have had so much fog and low cloud the genset has been getting a lot of unplanned exercise...

I suggest you need to be redo your calculations and  consider a battery twice as large ~8-900Ah@ 48V if your consumption will be that high... loads have a tendency to grow, somewhat exponentially.

Go for an OB , Magnum or Schneider inverter.  Aims does not have a good reputation, search here for Aims...@ 48V the field is limited...

hth

mayorbob said:

 220 would be hot water (though I am going to explore solar hot water heating),

I am assuming you mean evacuated tube solar water heaters, or only use solar powered opportunity loads to augment  your DHW gas heater.  otherwise VTmaps has it nailed.

I agree with vtmaps as well. Almost anything that converts electricity (water heater, stove, space heaters, etc.) to heat is a bad idea for off grid. I would seriously consider using a propane hot water heater, assuming you dont have access to natural gas, at least until you figure out your solar water heater and possibly to supliment on cloudy days.

mayorbob said:

I have ordinary appliances, such as coffee maker, microwave, blender, dishwasher, vacuum
<snip>
Then there is a washing machine, <snip>  dryer, <snip> printer,
<snip>
Then there is the hot water heater, refer & freezer (both smaller, high efficient, like less than 1 Kw/day) but looking at 12V refer & freezer & trying to compare power usage.

Do you intend to be doing laundry while vacuuming or using kitchen appliances?   If you expect to continue life as if you are on the grid, you should spend more time researching generators and how they interface with battery based off grid systems.   It is discouraging research.

Off grid is a lifestyle... either you will spend a lot of time managing loads, or you will spend a lot of time dealing with the generator.  Overall the power you generate for your lifestyle will cost 5 - 15 times what your utility bill would be if you were on the grid. 

By the way, I chose a battery that can not handle high wattage loads.... we start up the generator before we vacuum or use sustained high wattage shop tools.  I figured I needed a generator anyway (like for 3 cloudy days in a row), so since I have it I might as well use it.   I don't have any automatic generator start... they can be a real problem, especially in cold weather.  My generator is a 1600 watt portable that I keep at about 40° F in the garage.  I move it outdoors when I want to use it.   It can run anything I own, but of course, only one big load at a time. 

If I wanted to vacuum (1500 watts) for an hour on batteries, I would have to more than quadruple the cost of my system.   Because I would have so much more battery, I would need many more solar panels to charge the battery, and a much larger generator for the same reason.  The larger generator would not be portable, so I would have to build a heated generator shed for it.  It didn't seem worth it just to avoid operating my little generator for 2 hours per week.   By the way, when you are fueling your large generator you will get a sense of just how expensive your power is.... but when you replace your batteries, that's when you will really know.

mayorbob said:

couple of clocks...nothing that would really draw down a system.

Little loads for long times are big loads.   My 3500 watt 120 volt Outback inverter draws 20 watts when it is turned on and doing nothing.  That's actually a very low number for an inverter of that size.  But it does add up to 480 watthours per day.... that's as much as my ultra efficient refrigerator consumes in a day.

You need to get realistic numbers for all the little stuff.  Many of the items and appliances you mention may draw phantom loads.

mayorbob said:

So that's probably the best, at this point, that I can explain our loads. Does that help? Knowing this, how would you set up the battery bank?

You are asking for design and engineering advice... Great!  You've come to a good place for it.  Unfortunately us engineers work with numbers and formulas.   We need numbers for peak loads, peak sustained loads, and daily kwh consumption. 

By the way, don't be too discouraged... a 5 kwh per day system is doable.   The battery selection is the hardest part of the design.  It sounds like your peak loads are large relative to your energy use, so you may want to choose a low Peukert factor battery... they cost more than flooded lead acid batteries, but may fit your needs better.

--vtMaps

We've only been offgrid since July, but the lifestyle changes have been rewarding.
We're in a 1150sqft cabin, that's totally spray foam insulated. 12k btu minisplit handled cooling well with fans for extra circulation. Thus far we've not been below 84% batt with a 420AH bank according to data screen on CC. We're a little over paneled, but it allows for opportunity loads.