Advice for getting panels mounted

[foo1bar]

Put the first 3 panels on the roof.

BUT the right side is ~2" closer to the roof's edge than the left side.

Anyone have a best method for setting the panels such that they're not noticeably angled relative to the roof's edge?

With just 1 panel, the short edge looked parallel to the gutter - but after adding 2 more next to it, it's obviously not... So now I need to unfasten the panels, adjust them so they look right, then fasten them back down.

[sensij]

Chalk line? Tie up a string guide? Laser line? Sounds just like my first experience laying tile.

[inetdog]

One method that works pretty well, if the roof edge is smooth and square, is just to make up a spacing jig (maybe as simple as a 1x2 with a 2.4 block on one end) that can hook over the edge of the roof and show the spacing between each bottom corner of the panel and the roof edge.
If you are sure that you get the "vertical" rack elements parallel to the rafters inside the attic space you can simply use a framing square to set the panels perpendicular/parallel to the rack channels.

[SunEagle]

There is also a possibility that the gutter and roof edge are not at a 90 degree angle. If that is so you will have to decide which one you want to align your panels to.

IMO I would pick the roof edge since gutters have a tendency to move or are actually slanted for water to flow to one side.

[peakbagger]

Framing contractors have special tape measures that only read in inches . Roofs can be out off square so its generally a compromise. The lower edge of my roof bows out about 1.5 inches from the edges to the center. The best approach is snap a horizontal line from the lower corners of the roof from side to side then establish a perpendicular line at the center of the array. The best way to find the perpendicular is measure any multiple of 3 horizontally than the same multiple of 4 vertically and then measure the same multiple of 5 from the first two points so you form a triangle. Once all the measurements are exact, then draw a vertical line through the intersection of the 4 and 5 measurements. From that reference line see how it lines up with the edge of the roof.

Most folks don't judge depth well so you are better off being off horizontally than vertically. therefore you may need to rotate the horizontal line away from parallel with the front edge to get it aligned with the roofs side edge. That's one case were the new fire code in some jurisdictions help, that access way to the ridge pole between the edge of the panels and edge of the roof will hide a lot.

If you have multiple rows make sure you measure corner to corner to make sure they aren't racked. I have pole mount that racked a bit but I live with it as the adjustment would require a major effort.