For those who have electrical solar panels, Is tracking necessary for daily operations? If so, how effective is your unit? How reliable is the unit, and what about repairs?
When I had a system installed I considered tracking devices. There are two basic types I am aware of . . . one uses a refrigerant in tanks; and one is electrical / mechanical. The refrigerant type works on phase change due to heating and shifts the fluid between two tanks; tiltling the panels. The other type uses light sensors / motor(s) and mechanical gears. I've read that tracking can pick up ~ 10 - 40% more; depending upon numerous factors . . I would tend to disbelieve the higher percent unless it's some pretty bizarre location / conditions. Anyway; I ended up not doing tracking for a couple reasons. Didn't want to do the refrigerant type for environmental reasons. Didn't do the mechanical / electrical type as I was told by the installer ( well-known, long standing, and respected ) that ANY type of tracking will require at least some maintenance and eventually some repair. Never know when some crazed squirrel would choose to build a nest in the gears . . . probably on the coldest / windiest day of the year. I was also told that they had a tendency to not fare well in high winds. Having two, 100 sq ft arrays made me gun shy of doing it. Also, in my case; there were incentives through the state ( New York ) which were based upon PV wattage installed. If I had installed less wattage AND trackers and ended up with the same collected energy; I would have gotten a smaller incentive. Since the incentive was $4 / watt installed capacity; it was a meaningful amount.
I don't have any "real" info on actual reliability though; of any type of tracking system in any installation. Just sharing some thoughts / facts . . . I've had a nominal 2800 watt PV array in place for 2 years now; and collect about 2700 kWh / year here in central New York state . . . not the sun capital of the world for sure . . . .
I haven't been to Home Power's website / mag for quite some time; but I would guess there's some more "real" info there . .
I think Bob pretty well covered it -- just a couple added thoughts:
You should be able to get a pretty accurate idea how much tracking will buy you by running PVWatts with and without 1 axis tracking. For my location in MT PVWatts predicts a 30% increase for a tracked array.
One thing to bear in mind is that it gives much more benefit in the summer than the winter.
On the refrigerant driven ones, I know that Zomeworks (who makes this type) had to change the refrigerant they use to one that is better from an ozone depletion standpoint -- not sure how much better. There was an article not long ago in Home Power that compared trackers -- www.HomePower.com
Here is a link that might be useful: PVWatts