With some of the elaborate formulas out there, I can see why people might shy away from the audit. But if they want to be realistic with their goals, it is very necessary. While gasoline is still readily available, I found the gas generator and and battery charger combo to be a great way to bridge the gap until the full solar/battery setup is complete. When I eventually setup the battery system for the yet-to-be-built house, I'm goung to look into building my own 'tesla' home lithium ion battery. You build it from individual lithium ion battery cells that you buy in bulk. It's supposed to be less than half the cost so I'll crunch some numbers when the time comes. Thanks @preppervetuk :)