HouseWolf, you didn't refer to it specifically, but remember that you should not drain your batteries down to less than (about) 50% of their capacity. Lower than that rapidly decreases both the total capacity of the bank, and their life span. The way to deal with is - more batteries - more total capacity.
For example, batteries that are rated at 230-amp should be discharged no more than about 115-amps. Our boat has 460-amps total of capacity. We will use no more than 230-amps before recharging. (Speaking here about flooded wet cells - golf-cart batteries)
The total capacity of the battery bank you settle on can also depend on the voltage you choose to use, as you obviously understand. At higher voltages, you can get the same power out to your house with fewer amps out of the batteries.
You really should do at least a "quick and dirty" analysis of what your daily electricity needs would be. Take a look at the plates on the fridge and freezer, and note how many Watts each uses. Same for the fan motor of the furnace. Those are at 120-volt AC. Using that you can see how many Amps each item draws. Estimate how long and frequently each will actually run. Multiply together for total amp-hours needed from the batteries. This is where I gross the whole thing up by 10% or so, to be overly conservative. This tells you how big an inverter you will need - I'd suspect that 3,000 watts will be fine. But no curling irons or Kuerigs. Remember that your inverter will be no more than about 85% efficient, so you will now multiply all of the above by 1.15, to get the total amps you need out of your batteries, (preferably on a 24-hour basis.) From here, you can plan your battery bank and the PV panels you will use to recharge them.
Pant-pant-pant..... LOL And also keep in mind that you will want a "Pure Sine-wave output" inverter. Motors like in the fridge, freezer, and furnace just run more efficiently on sine-wave AC electricity, than on pulsed or stepped DC - (modified sine wave.)
Last edited by PlumBob; 08-06-2017 at 01:19 PM.
". . . for the time has come for you to awaken from your slumber. . . " Romans 13:11