It would seem that using solar panels for everything is foolish unless someone has a large amount of money to throw at the system. For someone whose house is too far from the grid to pay for the power company to erect poles or lay cable, solar is the way to go if it's the only way they can have electricity (no chance of using wind or water). The better approach would be to not have energy hog appliances, use firewood for heat, super-insulate the house and use LED lighting. If possible, a geo-thermal heat source or a generator could be used to augment the fireplace if the temperature drops too far.

I know someone who went off the grid around 1990- last time I spoke with him about ten years ago, he said he had replaced the batteries once and they were really nothing special but they weren't abused, either. He said they have a two story house with a fireplace on each floor but even in the worst part of Wisconsin Winters, they almost never directly heated the upstairs because the first floor was enough for the whole house.