We've been operating with 5Kw of solar panels on the roof, while 2.5Kw sat in the basement... waiting for me to get up the gumption to put them on the roof. I used my 1974 Grove crane to put the first 5Kw of panels on the roof, but this time I thought I would try it w/o the crane... thereby freeing up the crane operator (my wife!) to do other tasks around the house.
My panels are attached to the standing seam roof using S5! clamps. These clamps have kept my solar panels in place for two years through high winds and adverse weather, so I decided to literally go out on a limb, and used them in conjunction with 2x4's to build a chicken ladder on my roof. After reaching the peak of my roof, I was able to attach a rope to my (almost finished) chimney, thereby providing a higher degree of safety. I attached myself to the rope using a lanyard and a rope grab with a ratcheting action, allowing me to scramble up and down the roof fairly easily.
Then I started at the peak, removing the 2x4's one at a time and attaching the solar panels as I worked my way back down the roof. These 208 watt panels are heavy, bulky, and sharp on the corners... so even though my safety was assured, I had a hard time wrangling these panels onto the roof without scratching the painted roof. (I kept a bottle of automobile touch-up paint in my pocket) There were a few times I was genuinely afraid I would drop the panels to the ground. But somehow I managed.
The wires for my solar panels pass through a hole in my roof near the eaves. From the roof surface to the breaker box under the eaves, I used solid metal conduit. Anywhere wires from roof mounted solar panels pass through a habitable structure, metal conduit should be used. (fire safety) I wired my panels so that three panels are in series. In the breaker box, four of these "sets of three" are wired in parallel. Then two wires are required for 12 panels to get power to the basement where my MPPT battery chargers reside. (I know, I know, I need a schematic to explain this.)
As of this writing, I have six new panels (approx. 1250 watts) on the roof and wired into our system! The rope remains on my chimney so I can add the other six panels this week, which will bring out solar capacity up to 7500 watts.