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Forum Index : Solar : My solar farm
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
3 years ago I posted about my dual axis solar tracker on this forum see here and it has been working very well all this time. But my battery bank had gradually increased so that more solar charging was required to feed it  .
The only place for unobstructed all day solar at my small suburban block is on the flat shed roof so that is where the trackers are located. Due the wind loading anything bigger than a 2 panel tracker was asking too much of the roof structure. So I built 2 additional trackers  . There is method with this decision, the considerable amount of mechanical work - I built everything from scratch - requires lots of setting up so doing more parts makes sense. Also, 3 trackers offer redundancy and deal better with shade problems which, fortunately, only happens in the low winter sun for one hour in the afternoon. The offending tree 2 houses away can't shade all 3 trackers at the same time.
So, here is my solar farm: 
Another view: 
And a closer up view: 
I built a motor driven micro switch activator to temporarily replace the timer which lets me start a tracking interval every 30 seconds or so. This way I could run the trackers in my shed, doing a year's worth of tracking in only 2 days or so. This got all the bugs out of the system .
If you want to see this testing there is a utube video here: tracker testing Warning, it might be 5 minutes of not much action  . Utube was down a few minutes ago so I hope you can see the video clip.
As mentioned, my trackers are all dual axis and are purely electro mechanical, timer activated. At each allotted time the timer switches 12VDC to the gear head for exactly one minute and the magic in there does its thing, advancing the panels 15 degrees E/W and resetting itself to be ready at the next time slot. No control power at all is connected to the trackers during the wait time. The second axis activates once every 24 hours(Mk II trackers) and advances the sun altitude alignment by 0.25 degrees. That is a very small increment and took some tinkering to achieve. But, as my trackers are on the roof, I am saved the inconvenience to climb up there and adjust the altitude more often as single axis trackers require. You can see the panels are counterbalanced (MK II trackers) with lead weights thus I got away with using quite small 12V DC drive motors. They are similar to the hi torque ones Jaycar sells but theirs run too fast (140RPM) so I got mine from e-bay (40RPM) and at less than half price as a bonus. These motors drive a 120:1 worm gear via a spur gear reduction, the total gearing ratio is many thousand. The worm gears lock the assembly in position, I fitted a gas shock to prevent the wind rattling the panel frame on the shaft. The two Mk II trackers were turned on last Thursday for the first time, tracking the sun. I was quite surprised today, being overcast & occasional showers to see a max of 47 Amps charge on the Wattsup monitor. This equates to 1.3Kw which is 120W more that the combined panel wattage of 1.18Kw. In total I got about 5Kwh charge today, can't wait to see what's it with full sun all day. Klaus |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Looks impressive and way over my knowledge, so I can only drop jaw and admire. Read somewhere that trackers give 30% extra, but 2 axis trackers must give more. Hope that during storm roof doesn't go with those 3 sails. Do you have any extra mode to put them in 'survival' position should high wind be expected? George |
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| Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Klaus |
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