My experience with solar panels are..to throw them in the trash lol, never had good luck with them. It is true a lot of it depends on the camera, and over the years the tech has improved greatly on battery life in them, but I went with Tenergy rechargeable batteries many years ago and never looked back. I'm sure the ones I use are at least five years old now but they still work well, my favorite cam is an old Cuddeback Capture white flash and the D cell Tenergys keep it running for 3 weeks between charges, I just use a cheap Harbor freight charger on them and have had great luck even in cold temps.
I am not convinced on the infrared, red flash, etc cams and fully believe the white flash cams don't spook animals any more than the others..I've been in some pretty heated arguments over that but I have the pics and vids to prove it lol, I think noise is the biggest factor..I will not buy a trail cam until I can hear it trigger at the store, Gander Mountain is a great place to test cams, they will yank a camera out of the packaging on the spot put batteries in it and let you mess with it all day long before deciding to purchase it.
Wind moving trees and even long grass is something that is a problem, I try to use larger trees and remove any tall grass I can when setting up..but even one strand of grass can be a nightmare. One winter I had a cam set up on a feeder and was getting hundreds of pictures of what I thought was absolutely nothing, then finally after zooming in on the pictures I realized there were wood mice zipping around and triggering the cam.
I realize this thread is getting off topic on an R/C forum, but recently Wildgame Innovations said if I can prove that animals can see their product..I can have the test camera for free. I set it up in a dead stump that I hollowed out just enough to allow the cam to be mounted inside with just the trigger/lens showing..and here is the video I put together..needless to say I got a free cam lol.
https://www.youtube.com/watch?v=TRTbVueBOPM&feature=youtu.be
I also can't stand the horrible video/picture quality of anything but a white flash cam.
But, putting regular size trail cams in a nest box or den site is next to impossible, so I am always looking for smaller options.