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neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210
Posted: 12:42am 10 Mar 2011
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FYI. My (nominal) 3.6KW system on my D-I-Y tracker is being installed for the same cost as a 'supply your own bits' 5KW roof mounted system and it will have close to an equivalent output - perhaps even marginally higher.
Comparable quotes for a 5KW system are around $25 - 28K whereas as these D-I-Ys are under $8 after RECs.
That is around 25-30% of what the solar mobs charge. And 'we' expect the payback period to be 'under 18' months.
MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329
Posted: 01:51am 10 Mar 2011
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Crew
I've asked this before somewhere, but don't remember the answer: Is there any advantage to using a tracking flat mirror (heliostat) to reflect the light on panels mounted in a fixed position or am I dreaming?
. . . . . MacNothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas
RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495
Posted: 02:29am 10 Mar 2011
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I'm sure it'd work.
It may be easier to wire since all your panels will be firmly fixed.
I'm sure however, that it would be a lot more complicated to track. If your panels are say, 10 degrees off ideal, you're only down 1.5% - if your mirror was off that far, you will almost certainly have cells not illuminated and be down 50% or more.
You would also need a 2-axis tracking system I think.
Finally, mirrors won't reflect 100% of the available sun. (If they absorbed the IR component, that would help your panels a bit by keeping them cooler I suppose). But you also now have in effect 3 surfaces where dust and dirt will reduce the light your cells see:
1. Light reflected/attenuated through the glass over the panels
2. Light reflected/attenuated from sun onto the mirror surface
3. Light attenuated back from the mirror surface to the panels.
Large mirrors are probably cheaper than panels, but they'd add a considerable cost over directly tracking the panels, I'd think.
AMACK Senior Member Joined: 31/05/2009 Location: AustraliaPosts: 184
Posted: 09:13am 10 Mar 2011
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Hi All, I have been working on a tracker for a while with another members input. I have two reduction boxes conected together and it is driven by a 24 volt electric scooter motor.
The motor has an electric brake that must have power before it will let go so there is no chance of it turning.
The boxes I have are a 10.5 to 1 and the second is around 25 to 1. The scooter motor is conected to the 10 to 1 box and the 10 to 1 is conected to the 25 to 1..
This will be conected to a car diff that drives the mounted panels. It has been built before so it is not my idear to use the car diff but I think it will not brake in a hurry..
I am working on a pixaxe chip program and useing a real time clock chip to give the picaxe chip a signal to work from for timing. I have all the limit switches to put on it so if it goes wild it will not trash my panels or brake anything. I was trying to use a 08M picaxe but I ran out of inputs so I have had to look at 14's..
It is still on the bench and I keep looking at it when I walk past but I will get into it in winter as the day light hours get shorter and all the power you can get is a bonus..
AMACK
P.S I do have a posting on the PICAXE FORUM with microzed about it as that is where I have looked for advice on the picaxe programing..
*Note to self
1. Make it thick
2.Make it heavy.
3.Make it stronger than it should be.
4. Don't rush the first job as the second job will cost more and take mor
Joblow Regular Member Joined: 05/01/2010 Location: AustraliaPosts: 54
Posted: 01:05pm 14 Mar 2011
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I would suggest AMACK, that before you put it into service you consider adjusting the mesh of the pinion in the diff so that it has zero backlash, otherwise you may have a wind wobble on the panels The man who never made a mistake never made anything
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:14pm 14 Mar 2011
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I had 'wind wobble' on my tracker mounted panels due to worm gear back lash. Its hard to remove backlash completely from a gear box and still have minimum friction drive force.
I solved the problem by fitting two gas shocks angled against each other, one of which gets gradually compressed as the panel turns, the other releases but both keep the 'wobble' to a minimum.
This has to be set to allow the full panel rotation but is doable with reasonably long shock rods.Klaus
Joblow Regular Member Joined: 05/01/2010 Location: AustraliaPosts: 54
Posted: 11:50am 15 Mar 2011
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I would agree with Tinkers post except for the difference between a worm/wormwheel type box where there is usually no adjustment of the clearance between the two elements, a hypoid type (diff) however can be adjusted to zero clearance. I can't see that any more power would be required to drive this (diff type) arangement than the energy required to overcome the shock obsorber friction, especially as AMACK would have ratio of ~250:1 before engaging the diff which would then multiply it by about a factor of 4 making the total reduction ~1000:1 The man who never made a mistake never made anything
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