You need to be dedicated and disciplined about maintaining your battery bank. You can lose a ton of capacity for storing power if your batteries aren't healthy.

This is more than just checking the water level (although that is vital), it's learning to test the specific gravity of each cell and the voltage of each cell to test for sulfation. It's learning how and when to do equalization charges, etc...

Archeon: unless you want to invest the time to do this, it'd be better to just go grid-tied. There are a lot of other advantages to being grid-tied also, like having enough power to cover spikes in your normal usage or to compensate for inadequate charging due to several cloudy days in a row. At the very least, I'd put in a switch to be able to revert to the grid if your batteries are depleted (some controllers can do this automatically.)