Solar PV panels are clearly more efficient at converting sunlight to electricity if they are mounted on racks that rotate to track the sun's apparent travel across the sky. However, tracking mounts are more expensive than static mounts and typically need to be installed on the ground rather than on a roof. Both active and passive tracking systems are available. Both seem to require more maintenance than static mounts because of the moving parts.
Do tracking mounts improve the return-on-investment of a home solar PV system after installation and maintenance costs are factored in? If the answer is "yes" in some cases but "no" in others, under what conditions do tracking systems improve ROI?
Update: After reading this answer, I played with the NREL tool Nate recommends for a couple of minutes and it looks like 1-axis tracking has more of an advantage over fixed arrays than 2-axis tracking has over 1-axis. So even if one is cost-effective, the other may not be depending on initial and ongoing costs.