I've got about $40K in my off-grid system, which includes 18 panels, a big honkin' battery set-up and a 5Kw propane generator. That compares to $65K to bring the grid to us. Has we brought in the grid, we'd still have heated with propane as the cost for electric heat is brutal up here.
The system is dreadfully overbuilt, but winter in Colorado can be serious business. We went through a lot of debugging last winter and replaced some of the components...when I tried to save a few bucks, it invariably came back and bit me in the ass. The system works and works well.
Of course, the whole house was designed for off-grid. it's passive solar, which is huge, over-insulated and heated through radiant floor heat powered by propane. We paid 2X for the boiler, essentially the top of the line. That has paid off in spades on propane usage. Kitchen, laundry room, and guest bathroom hot water is provided by a traditional gas-fired water heater; master bathroom hot water is from an on-demand European boiler — one again, 3X$ what the builder suggested, but 5 times more efficient than the cheaper units. There are, BTW, 2 separate systems providing the propane from 2 separate 500 gallon tanks. I wanted the tanks connected by manifold, but the builder never understood why. I'm having the manifold installed this summer. The master bath hot water and back-up heating are the only things on one tank. I could literally heat the house for a month or more off the back-up.
We have no AC, but that hasn't been an issue. It's 87 outside now, 73 in the house. Last summer the house only hit 80 degrees for 2 days when it was 100+ outside.
I would like a larger generator, or a back-up generator. I've looked at some reconditioned military diesel generators that could survive the zombie apocalypse. Most of the generator issued were solved by changing out to a more expensive computer to control the gennie. The one we originally had was more designed for RVs or remote cabins. The new computer head allows us more leeway in telling the generator when to fire up (for example, under the old computer the only option we had was setting a threshold voltage on the batteries to have the generator fire; a better way is to set a slightly higher fire voltage but only after a longer period of time, which allows the generator to head off any chance of the batteries hitting "shut down" voltage).
I talked to Buz Mills at GUNSITE, who has a spectacular off-grid system, about the Tesla batteries, but there's just not enough info yet. I sort of had an idea for a back-up battery set-up separate from the main batts.
Sorry to rattle on so long...
Michael B