Output calculators vs. real system output

[solar_dave]

I didn't see anything in that document that "requires" a licensed electrician/installer. It did make clear that there are a lot of regulations that one must be careful to follow at every turn, so I can see how professional help is advisable.

Most likely to get it commissioned you may need a licensed electrician. Many states do allow you to do your own wiring however with the proper permits, but sometimes it is just easier going if you have that licensed guy.

[Lee Dodge]

I have a section on my website that directly addresses your question, although it is a comparison of PVWatts V.2 predictions, not the model that you used, versus measured energy from three systems all in the same area:

http://www.residentialenergylaborato...v_systems.html
Not sure the link above will work correctly, so I'll list it again here:
http://www.residentialenergylaborato...v_systems.html

The results that I show should not be considered typical, but there is text in the document that reviews literature for some of the typical results. Basically my system produced more than 23.8% above PVWatts V.2 predictions, and two other systems in this area looked similar. More typical results are +-10%.

[jagec]

I have always intended to have the final hookup from the grid tie inverter to the meter to be done by a licensed/bonded/insured electrician. I would also have him check all the work on the rest of the installation. I would be interested to know whether the federal rebate requires a certified installer. I haven't seen that in any of the documentation I have been reading through. Do you know of at least one rebate that requires that so I can go see how it is worded and be on the lookout for it in my state/municipality?

It's the city code guys and the power company itself that care about UL listings and using a licensed electrician. If you have any state or local rebates or credits, they might care as well.

The IRS form just asks (1)How much did you spend on solar electric equipment and installation? (2)Multiply that number by 0.3, there's your credit.