Sep 12, 2008 10:45 am
Re: Declination, Elevation, Complication -
After re-reading these postings, I glimpsed a mental picture of what might be your predicament.
Its not just the angle to the horizon you are wanting to know because that angle is compremised by the pitch of the roof as well being on the westerly side of that pitched roof.
In my area, I have noticed this same predicament on several homes with solar water heater panels.
Again, it would take time, but I believe a, full sized plywood mock up of, one of the PV modules you would like to use, would give you a first hand, clear result of the best angles. It would also cast a shadow from the top of it, onto the roof behind it, so that you know exactly where to start the next row.
Another alternative, although very costly, would be to frame and finish, two walls that would saddle the roof. One wall would sit parallel to and over top of, the end wall. It would support the bottom of the array The other wall would run parallel to the first and sit just behind the first. It would support the adjustable or fixed brace arms of the array.
This what I "had to" do on my roof, almost.
I built out short walls, 6' long and about 20" high, leveled off of the peak and at an angle from the peak that put the array facing solar south. Since the weight of the array has the tendency to push the wall away from itself, towards solar south, I pitched that side down to the roof, creating a valley. The back or north side just goes straight up. The walls are finished with; plywood, flashing's, siding and shingles to compliment the rest of the house. Of course it all still looks like a big "billboard" on top of my home but I don't care. Even though the PV "harvester" is by no means free, I am getting the most photonic particle electrons I can from our Sun.