Step 4: Adding the linear actuator
I purchased the 12 volt linear actuator on Ebay. It's built to hold up in the weather, is strong enough to move however many panels I would want to add to it, and has a long enough stroke to move the panels all the way from one side to another. (I think the stroke is 8", but I'd have to double check.)
I mounted it on the one side of the frame with a through bolt, and attached it to the movable solar panel frame. To mount it to the side of the frame holding the solar panel I just used a staple on the board that moves on the bicycle wheels. A short piece of cable goes through the hole on the linear actuator and the staple, and iIused a small cable clamp to secure it. This allows everything to move around and flex as needed when it's moving. When hooked to the battery the actuator moves the panel all the way to one side, and reversing it moves it all the way back.
The next step is giving the tracker the smarts to know when and how much to move.