[jeff5may]

For a small system, grid-tie is much cheaper and more efficient. For every watt you feed to a battery bank, you will lose close to half a watt between charging on the way in and discharging and inverting on the way out.

Battery banks were made for people who have no grid power, like remote regions and marine/mobile applications. If you are a doomsday prepper, then of course none of these notions apply. But in the global system picture, batteries cost money and energy.