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brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548
Posted: 06:51am 20 Mar 2012
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OK, I've been reading your posts for ages now and feel that you guys are very smart cookies...
So, I'm about to challenge you -(I'm ok with tools--a dunce with them electron things whirling about)..
Could some of you start a thread on building a simple ,but fairly effective SOLAR-TRACKER ? ..
I'm sort of ready to install mine (yours) and would really appreciate your help ..
I can put it together ,no worries. If you guys could bug each other and come up with a nice Cct,then that would be fine ..
I'll watch with interest and hope you come up with something ,thanks
Bruce.Bushboy
Dingdoc Regular Member Joined: 23/09/2009 Location: AustraliaPosts: 76
Posted: 09:05am 20 Mar 2012
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Hi Bruce
Have you seen the circuit in the 'Circuit Notebook' section on p 58 of the Jan '12 Silicon Chip?
It uses a Pic16 micro with the code available for download on the SC website.
Trev
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 02:37pm 20 Mar 2012
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Well Bruce, there's two ways to track the sun.
The more complicated system aims for the bright spot in the sky and achieves 100% tracking unless the sun is hiding. In overcast or intermittent cloud situations I assume the electronics and servo do work overtime . This system requires power to run all the time.
The other system and the one I am working with is timer driven. I already have a 2 panel (440W total) system on my shed roof tracking for over 2 years now and its been giving a great performance. This system - in my case - advances the panel each hour by 15 degrees. It does this advancement 1/2 hour before the sun reaches the optimal angle so the error is never greater than 7.5 degrees, a very acceptable compromise.
Power to the control electronics & motors (its a two axis tracker) is on for only 1 minute each hour for the 120 degree tracking arc. The actual panel movement only takes a few seconds BTW and consumes a very small amount over a year of tracking.
The rest of the time the system is completely dormant other than the electronic timer which runs on 24V off the house battery bank.
So, which one is your choice? Klaus
grub Senior Member Joined: 27/11/2007 Location: AustraliaPosts: 169
Posted: 08:24pm 20 Mar 2012
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Just out of curiosity Tinker, do you notice "steps" in power production as your tracker steps across the day, or is it relatively smooth?
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904
Posted: 01:52pm 21 Mar 2012
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Smooth I would say. I actually once was right next to the Amp meter as the solar panel started to move, the battery bank charging current changed by about 0.1A that's all I could see. The fridge was running at the time so the battery bank had a drain of about 7A on it.
Summer daily output into the batteries is about 3Kwh, which is what I drained from them during the non solar charging hours. 3Kwh/day from 420W of solar panel is not too bad IMO. But two more trackers of similar size are nearly finished, these should keep the batteries full even on overcast days. With just the one tracker I do some load shedding now to prevent the batteries from discharging too low.Klaus
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:19pm 21 Mar 2012
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The difference between having a flat panel facing straight at the sun, and being fifteen degrees off would be negligible.
Many ways to build a solar tracker, but the one I admire the most has to be the simplest, easiest to build and the most reliable. And it requires zero electrical power to operate and almost no setting up.
It simply uses weight transfer between two interconnected propane tanks.
The two initially half full tanks are arranged on a see saw like free pivot, with the pivot tilt axis set to latitude angle, to track the sun across the sky.
Each propane tank has a solar shade fitted, such that the proportion of sunlight falling on each tank changes with the suns angle with respect to the direction the panel on this see saw is facing.
Propane boils away from the hottest tank that has the most solar exposure, and condenses into the cooler more shaded tank.
Propane vapor transfers between the two tanks through a common interconnecting pipe. The weight of liquid propane shifts accordingly from the hotter tank to the cooler tank.
The centre of gravity moves, and the panel tilts, always following the sun.
All it then needs is a fluid damper (automotive shock absorber) to prevent the whole thing flapping around too much in the wind.
For stability, the centre of gravity needs to be kept reasonably below the pivot axis, but with a bit of care it should still be able to fully track the sun from horizon to horizon with just a few Kg of weight transfer.
Not my idea, but absolutely brilliant, and anyone can make this fairly easily with few tools and for very low cost.
http://www.redrok.com/elcheapo.htm
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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. This system requires power to run all the time.
