Am I Doing the Numbers Wrong?!

why do you need that many?  are you aiming for 100%?  If you are, why did/would you pick shingles? 

What is your goal for your proposed photovoltaic adventure?

a. to save money
b. to have photovoltaics because you want to

if the answer is "a" money is better spent on conservation and efficiency, unless you want a payback over a 12 yr + period.  if "b", then, with most folks it comes down to system goals,  budget, or space that drives system design.  Very rarely do folks aim for or achieve 100% of loads covered on a grid tie system.

what have you done for efficiency and conservation thus far?

no matter what pv you pick, you are looking at about a 7kw system assuming you want to meat 100% of you loads.  That is likely over $50k, and probably more space than you have.

i'd love to hear your thoughts, and yes, your math was pretty close on the array size.  I came up with 411.

james - Alt-E staff