Anyhow, after overcoming a variety of obstacles, the fan is installed and venting heat from the attic, thereby cooling my upstairs to the tune of three or more degrees, woohoo! Obstacles included having to install the 10-watt solar panel almost all the way across the roof to where it was exposed to direct sunlight, because the tree on the south side of the house provides a great deal of shade to the roof: Good for keeping things cool, not so good for powering a solar panel. This entailed cutting and splicing another 18 feet of wiring into the power supply, running said wiring beneath the roof's crown shingles, and sealing the shingles so no water gets beneath where they're raised slightly for the wiring.
The attic would have been unbearable to work in this afternoon (was cooler when I installed the fan part in the morning), but the roof wasn't much better. I wore a wide-brimmed hat and sunglasses, but also gloves because - WOW! - roof shingles get hot in Kansas August! Even with half of 'em shaded. I have a multitude of lacerations and bruises from the composite roof, including a doozy of a bruise along one side of my chest from leaning over the edge of the roof while drilling and screwing fasteners into place.
But it's done! And my house has moved 10 watts into the future!
I'm expecting not only that my upstairs will be cooler, but that my elecricity bills will be smaller.