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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.

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    This isn't really a proper answer: one situation where trackers make a lot of sense is where labour cost is low and panel cost is high. In the much of global south the "cheap" panels we talk about are a years cash income or more, while a simple stand made from local materials is cheap. Having the person who operates the panel (and sells, say, cellphone charging) periodically re-orient it to track the sun makes perfect sense. For larger installations having a twice-yearly adjustment between summer aspect and winter aspect can help eke out a few extra joules.
    – Móż
    Jul 11 '13 at 0:09
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Generally, no they're not.

For a combination of several reasons

  1. the tracking system itself has a high capital cost.
  2. static PV systems are extremely low maintenance. Tracking PV systems are not.
  3. adding a tracker means bigger spacing between groups of panels, so that they don't shadow each other
  4. The net additional energy yield isn't that high: for PV, ambient light is pretty much as useful as direct rays. That's very different to CSP (concentrating solar power), where it's all about the direct rays.

These all come together, to mean the economics of a tracker don't work - it's extra capital cost, and extra maintenance cost, for little extra benefit.

Panels have dropped much more in price than the rest of a tracking system has, so if you want more power, it's much cheaper just to design the system with more panels, than to get extra yield by adding a tracker.

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    The extra land cost of a tracker is also a factor for most people. Roof-mounted tracking systems are rare, largely because the extra difficulty of maintenance access makes them unviable. So they get ground mounted. One tiny offsetting advantage of a tracker is that you can grow sun-sensitive veges underneath one, and they'll benefit from the partial/intermittent shading.
    – Móż
    Jul 11 '13 at 0:03
  • If a given homeowner is generally technically capable & often home, maintenance for single-axis trackers can be dealt with easily: the primary reason solar installers and integrators have avoided trackers has been that the most common failure modes result in the tracker canting sideways to one or the other arc endstops, meaning that array then runs at worst efficacy through most of the diurnal cycle until repaired.<br/> If the owner is observant, has the skills, and repairs the given tracker immediately, typical gains are ~ 20%; this is why more panels is a better bet for the $$.
    – GerardFalla
    Mar 13 '18 at 14:51
  • What about a twice yearly adjustment of racks to maximize for winter and then summer?
    – Graham Chiu
    Mar 14 '18 at 0:09
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If a given homeowner is generally technically capable & often home, maintenance for single-axis trackers can be dealt with easily: the primary reason solar installers and integrators have avoided trackers has been that the most common failure modes result in the tracker canting sideways to one or the other arc endstops, meaning that array then runs at worst efficacy through most of the diurnal cycle until repaired.

If the owner is observant, has the skills, and repairs the given tracker immediately, typical gains are ~ 20%; this is why more panels is a better bet for the $$!

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