While most of the project went pretty smoothly, there were a few glitches:
Being an early adopter of new technology can be risky. The early-generation enphase microinverters I used initially were subject to high failure rates, which the company blamed on poor quality control. Fortunately, they replaced all of the microinverters free of charge whole they were still under warranty. Newer generations are claimed to be much more reliable, and come with 25-year warranties.
Enphase published one or more white papers suggesting that you undersize your microinverter relative to the solar panel wattage. I did this, and suspect that it may have led to premature failure of microinverters. DON'T MAKE THIS MISTAKE!
I should have coordinated more closely with the electrician during the planning stage to save some hassles with swapping out electrical boxes, wiring, and associated components later. We ended up up-grading in this case, so that it probably is not a problem for the utility company.
I ordered more racking equipment than I needed. Proper planning could have saved me some money and some hassle.
We should have covered the PV modules with cardboard to prevent damage from dropped tools.
The heavy duty hook on my roofer's safety harness needed to be covered by some soft fabric--at one point it landed with a considerable impact on one of the glass modules.
Ready-made flashing might have been a better and neater solution than the on-site made flashing for the roof attachments.
In the future, I would not use the same theft-resistant fasteners I used for this project; they tended to strip out at the recommended torque levels from the racking manufacturer. If I need to remove the modules in the future, it will be challenging.
DIY Solar does not necessarily make solar more affordable these days. Renewable Energy Credits (RECs) are not available to you if you installation is not performed by a certified solar installer (certified by the North American Board of Certified Energy Practicioners--NABCEP). RECs can reduce your cost by up to 30%, so carefully consider this fact before leaping into DIY solar.
There were also positive lessons:
Extensive planning paid off with a pretty smooth project.
Purchasing a kit simplified purchasing and planning. I highly recommend purchasing a kit. Be sure of what you are getting, though--some kits do not supply the racking materials--a significant extra cost, especially for thin-fim photovoltaics.
Leaving space between rows of panels made maintenance easier.
It absolutely helped me to have class room and hands-on training from expert installers from one of several sources:
Solar Energy International (SEI): http://www.solarenergy.org/
Illinois Solar Energy Association: https://illinoissolar.org/Illinois
Midwest Renewable Energy Association: https://www.midwestrenew.org/
The guys at the electric utility and the town zoning board were helpful and supportive. Following the requirements from them minimizes hassle later.
If you are not a certified electrician it makes sense to hire an electrician like I did.