I've been living with solar exclusively for 10 years... to Laura, I suggest a Kill-a-Watt meter($25-$35) and plug devices around your home into one for a few days or a week at a time. It will give you a good idea of how much power each item you actually have uses. Big thing I've found with solar- do with what you have until you can get more. There's no across the board formula that's going to be accurate in every situation- solar exposure varies(both by latitude and average cloudy days/year), not all panels degrade at a predictable rate, some batteries are better than others, wiring, inverters, distance- all contribute to inefficiencies. If I had to give simple advice to someone taking the plunge, it'd be two fold: A) take the plunge, B) assign a budget for your solar system and learn to live within it's constraints.
For what it's worth, I run a meager 1.2kw w/ 2250ah in battery(never use more than 30-40% and run an electric kitchen. I'm taking a break from the 100 degree heat with a window unit blaring on me and run power tools constantly.
To Ben: GOOD.
I KNOW systems like yours have a place... $25 does not seem too much at all- I really think it's low, particularly if it was a well-thought out how-to instead of the typical online 'downloadable pdf' or poorly photocopied/stapled packet. I worked for a company that handcrafted(garage level engineering) self-contained boat dock power systems that were approved by the Corps of Engineers, though much smaller. Built around quality components(Xantrex, Kyocera etc..) and ranged 85w to 260w incoming with only 450ah max in a lockable aluminum dock-mounted unit. Business was good until everyone that wanted one had it. They don't wear out fast, hah.
Too many positives- it's easily modular, could be built in a range of configurations(500w to 2000w or so?) and adjusted to compensate for solar insolation... Can be made very secure, etc... Only thing I'd offer- Stick with lead-acid deep cycles. I'm paying about $150 for t-105's these days but finally got an 8 battery bank of AGM's with similar specs to do the Pepsi Challenge with- they just don't take the punch. I'm fine checking and adding water as a monthly routine in exchange for the added 20% or so I can squeeze out during those long stretches of cloud cover come December(I never actually run them too low).
Cheers and BEST of luck.