Thanks...the house we're building next spring is in Central NY (in between Syracuse and Utica). More concerned about HEAT in the winter than A/C in the summer, but they're both drains on the system. We'll either be using SIPs or 6" spray foam insulated walls. My *assumption* at this point is that even if I can get the system installed (off-grid) for $25k and it lasts 10 years, the battery costs should come down during that 10 year span so that when I do have to replace them in 10+ years, it will be less.
$25k spread over 120 months (10 years) is $208 per month, but right now I'm averaging about $150 per month, so it's a bit higher.
Oh sorry, Central NY is entirely different than TX which I had assumed. That really opens up more options to choose from.
If you want to be off the grid a heating system that uses very little electric would be the way to go. Radiant in-floor heat takes only a bit of power to run the circulation pumps and boiler assuming you use NG, LP or wood as fuel. If you are willing to feed a wood stove that can be your primary heat system with something to back it up when you are gone. In tightly sealed modern homes you really need to have an air exchange system and there is no getting around powering the blowers with electric for that. You will need some AC too for 3-4 months in summer.
A gas water heater, clothes dryer, range & oven goes a long way in reducing your electric use. On or off grid a generator would be a smart investment. Off-grid I would consider it a necessary part of the system. It allows minimizing the battery capacity (i.e. 1-2 day versus 3-4 day capacity to get you through low solar periods like three days of very gloomy weather) and is the back-up for any component failure. If you want to use high power tools like a welder or large motor equipment size the generator to handle those loads.
I think a lot depends on what sort of home and lifestyle you are aiming at. Getting off the grid for $25K will be a challenge I believe. I would get quotes for complete 6 kw and 8 kw systems (DC solar panel rating) including batteries and see where that lands. That size system should be doable without giving up much if anything.