We began the installation on a cool morning on April 20, 2011. After some discussion about the project, we figured that most of the first day would be consumed by installing the rack, and that anything more would be "gravy". So Steve, a jouneyman electrician from Current Plus Electric (http://www.currentpluselectric.com/), operating out of O'Fallon, Illinois, worked with me to accomplish that. Sure enough, it took most of an 8-hour day with just the two of us.
We used a long,skinny electrician's bit to probe through the roof and roof deck near the marks I had previously measured to find the roof trusses. We then used appropriate sized bits to drill the lag screw holes.
Although the kit came with a certain number of "L-feet" to fasten the racks to the roof, I opted to order a few extra to ensure that the high winds we some times experience did not rip the array off of the roof. Most of the L-feet are on 4-foot intervals, with some near the ends of the racks or adjacent to splices at 2-foot intervals. We squirted some high-quality roof sealer into the screw holes, as well as the bases of the L-feet, and lagged the L-feet (already attached to the rails) into the roof. Naturally, we had to adjust the location of most of the L-feet to get them to align with the screw holes in the roof, but I believe using the pre-assembled rails and adjusting the L-feet this way was less hassle than chasing dropped nuts and bolts on a roof.
After the rails were secured to the roof with one 3-1/2" long stainless steel lag screw through each L-foot, we permanently spliced the rail sections together with the special splices supplied by Unirac. We secured these with self-tapping screws to ensure a good electrical ground.
At the end of Day 1, we had installed all of the racking,
and had flashed and sealed most of the roof penetration points.
You can see additional photos of Installation Day 1 here: