I have been looking at this calculator to get an idea of what size system I should install
http://pvwatts.nrel.gov/pvwatts.php
I am just wondering how accurately something like that has predicted your output.

The State of Washington just extended their solar incentives program and are guaranteeing 8 years of incentive from the date of install, but the amount is based on how soon you get it installed ($0.16 per kWh if done before 6/31/2018 and it goes down annually from there). So, I am contemplating doing a self install (you already told me about renvu.com in a previous post and I am pretty handy). I also have a group of a couple other professors at work who might go in together to both get a better deal on materials and to help each other perform the install. We figure if we have 3-4 ME professors who are quite "handy" and my 13 year old as a runner, we could hammer out all three installs in about a week.