Each brand has a spec sheet for comparison. Another point to be wary of (wire size) is that they perform better in colder temps. The spec sheet will give you an average temperature for reference, but thet will underperform or over perform based on temperature.
My panels are mounted about 3-4" above my pilothouse roof. I've not had issues with bird nests underneath. However, I'm in a different geographic area.
My panels sit about 2" off the cabintop. No issues with birds or anything. I apply spider spray under there periodically and that's been enough to keep spiders to a minimum.
Might sound ridiculous, but I have found that rubber snakes work-probably the only deterrent that would fit under the panel. Seagulls were using my upper deck as a dining table. I put a black rubber snake and a coral snake on the deck and the problem was solved. I wouldn't think a coral snake would work in the PNW, but I saw a seagull start to land and then radically veer off when it spotted the snake.
Forgot to add that I moved the snakes about once a week and changed the body position-coil, uncoil etc. learned that after watching pigeons sit on plastic owls.
