Thanks for the replies everyone! The discussion has given me new things to think about.
@Radman: Good idea, I'll look into the polarized lenses. Could easily get a cheap pair of sunglasses and fit the lens over the resistors and compare observations with / without. I'll look into that more - thanks for the idea.
@Graynomad: It will be "remote" in the sense that is will be in my backyard, probably under a roof overhang inside an enclosure, but located not very close to any AC outlets. My options then would be to drill a hole into the garage and run an extension cord in (I don't want to do that) or to use strictly DC power through batteries or solar or some combination. Because the arduino and other sensors will be under a roof overhang, I was thinking a U shaped PVC arm could be built to take the solar panel past the overhang and up higher than the roof.
I agree about the sanity test. 1 or 2 days of constant rotation would probably wear a servo motor out. Perhaps some code logic could be used to say something like, if I start a timer when it starts moving, if it has 2 minutes of continuous rotation, then go to a set position and wait a couple hours? I'll look into the tables you speak of and see how I might be able to apply that to a servo to match sun position.
@Far-seeker: That's a good point about the temperature of environment affecting batteries. Houston is usually hotter than it is cold, but there are a couple weeks of the year where we might see freezing temperatures and that could be bad for the batteries. I absolutely don't want to have a heated enclosure - don't want the fire risk of a heating element. I'll start reading about SLA batteries - thanks for the tip.
On the suggestion of a voltage regulator: I agree that's a good idea and I'm not familiar with how they work. If I have a solar panel that outputs 9V in daylight, that voltage level will obviously fluctuate depending on time of day and clouds, etc. The 9V should be good for an arduino to run on, but do arduinos handle the voltage fluctuations? Would it be better to regulate it back to a constant 6V? Or perhaps run everything off of the battery and only use the solar panel to recharge batteries during the day?
Thanks everyone, this has been a huge help!
Robert