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24 x 450W solar tracker


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My slim line solar tracker. X-Y for 24 solar panels.

My system was approved for pushing power into the network.
Now to get a few of these build and install +/- 100 450W panels for my inverter.

This is the basic unit and gear.  The cost is +/- R 2300 with two motors that costs R1600 for the two. As I assemble I will show more.  The gear is made from 30mm thick EN19 hour glass with a 40mm worm.  +/- 70 to 1 and very strong teeth are  8mm deep. An external gear is mounted with an additional 3:1 reduction.
The bearings is my own design with a severe reduce in cost. It is designed to fit on a standard 200mm sched 80 pipe.

It is in a permanent oil bath to fight the west coast weather. ( I live opposite the sea) . This device has a certificate (COC) for up to 18M in height.

If it is boring tell me and I won't publish more info as I do the installation etc.



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The following two photos is of the "Oil bath" in the 200mm Sched 80 pipe followed by the pwm for the motors. The PWM works up to 30VDC and handle the X & Y tracking. The "Funny way of drilling is because I streamlined the old design and then had to make it fit.




The oil bath section.  20191001_162711_resized.thumb.jpg.ff0f6ee3a5267c2ce7050365cbdc4df4.jpgThe "Funny way of drilling is because I streamlined the old design and then had to make it fit.

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The efficiency curve  X axis is % power used/supplied by inverter.
Y Axis has three graphs Vmin V mid V Max of solar panels.
It has a very wide Voltage input range. The Vmin(blue) - Vmax(Yellow) delta is 400V.
I made a mistake in the first part of the postit is 500W solar panels not 450W. I had a 110 manufactured for me @ a cost of R205 800 ex Vat or R 4.20 per Watt keep the change.  R2100 per 500Watt panel and the total amount generates just over the R10 000 per month.


Edited by Erastus
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4 hours ago, Erastus said:

I had a 110 manufactured for me @ a cost of R205 800 ex Vat or R 4.20 per Watt

I didn't realize that having your own panels made was :

a) possible, or

b) cost effective (your price is under R4/watt - vat exclusive, which is remarkably good - (group buy good)).

May I ask why you chose to go this route, and which supplier provided this service?


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I took this route for a few reasons:

  1. Solar panels are to expensive in SA
  2. Inverter I designed that operates differently to the ones you buy as I use no MPPT or other equipment. The solar input delta is 400V DC.
  3. I have a height restriction so the mounting is important. Therefore I had to work with in the law and I wanted it to follow the sun as it generates 35 - 55% more energy.
  4. Once complete it will be available in a kit form so that others can push back into the grid. My way of toy toy.

It took some time to get all approved. After signing a contract with City of Cape Town to "sell" electricity if one consider spending +/- R300 000 and saving R3500 electricity and then earning R10K per month = R13K5 The ROI for 5 years is  R810 000 - R300 000 = R 510 000.
Thus when breaking the back of the cost of the solar in SA it can be used as a supplement to normal income.

The first "breaking" point was to make sure the solar inverter system cost is low. My own design a 10Kw unit scalable from 1KW - 10Kw did the trick.  When I was quoted R 130 000 for a +/- 7Kwatt system I realized there is potential. Battery Chargers etc are stupid stuff and easy but during the design I was amazed to see how dumb an inverter actually is.

Then I also did the design as my hobby is electronics and it paid a handsome return.



The Tracker will be available soon. I spend time on the design to minimize other equipment cost.  Schuurman Lazer cut in Cape Town was very patient with me. I never did any steel stuff before. With their help I could stream line it down to this size and make it part of the assembly and not an add on. Thus I bought some used Sched 80 200mm pipe 1M and that created the base to mount it.  My new units will be mounted on a concrete column.  I did the calculations with the first design and it worked well and then learned from that and started to stream line it. I made sure to minimize cost I need to cut labor as people don't like working in SA. Thus the only work after the cutting is welding the case and tapping 14 wholes for the cover. It is made from 10mm steel and stands firm against the South Easter and North Wester in Cpt. A single bearing ins SA was R 480 from BMG and I needed two and that means too expensive.  So I asked a few questions and voila now I got my own bearing at R150 for 2 bearings.

This is what the worm and gear looks like. When looking at the stuff REMEMBER I HAVE 0 mechanical experience so make suggestions please.
I am not sure what it will cost to mount 24 panels it will be hard to beat this combination.

Therefore everything I did was to drive down cost and labor.  The next lot will be a kit from Shuurman engineering. I also uploaded the load and stress calculation.




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1 hour ago, Erastus said:

After signing a contract with City of Cape Town to "sell" electricity

thanks for posting this. Hopefully we will soon all be able to viably sell our surplus electricity to the CoCT. How much did they offer you for a kWh? What about the law that Cape Town is forced to only purchase electricity from Eskom? Has this been changed? Or do you still have to be a net electricity consumer? 

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All I can tell you is that I have a signed contract for 11KVA and forgot the amount I receive for Kwhr. I have to check on my contract.
My system was approved and then they installed a 3 phase bidirectional meter (My original was removed).
Currently I sell to City of Cape Town and nothing stopping you. The formula they use is a 1/3 of power supply. They have a sensible explanation for the 1/3.
I have 100 amp per phase and 3 phase into my house. 
Thus it is 11KVA or 10 Kwhr rule of thumb.
This was the first month I received a -Rxxx for electricity used from the COCT.

My time line is a little longer as I designed many things for my system.

Edited by Erastus
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I remember the last time we discussed this (some tempers flared... I am truly sorry for that). I still think this is a very clever idea. If you hold the PV modules into the sun all day, the traditional bell curve becomes very fat and the MPP almost doesn't move the whole day. If you also match your voltage requirements, then you're basically addressing all the problems that you normally cover with an MPPT 🙂

Really really fascinating. Though I think the real story here is that tracker. If it is cost effective... it will sell 🙂


Edited by plonkster
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I never saw it as any tempers.  No need to apologize. A lot was said that I took and re-looked at the design.
Those arguments from every one even when I was told I can't proof it suited me 100% it had the desired affect and the pit falls was highlighted from the arguments.
I understand that all people does not understand electronics and it is my bread and butter.

I now know and understand the wasted cost in solar design and that made it all worthwhile.  I could not understand why solar is that expensive. Today I can say me and my neighbor has free water from the sea via a small Reverse Osmosis plant on my roof we both have free water.  Now I get paid for electricity instead of paying the  politicians from the COCT.

All I did is made sure that the input voltage has a huge range for easy words (not technical) a variable Z (impedance) and the rest is dumb electronics. The most important is the CPU as it is a dual core 200Mhz with FPU and multi channel DMA for ADC and DAC which is programmable with trigger points and shared memory.  And then it was easy to create the cheat.
The 10Kw 3Ph inverter is +/- R 8K.  Do the math's and understand I do not drive a 4 x 4 but an old beat up tjor.  🤪

If I do put a MPPT in between I loose another +/- 3% efficiency and the cost escalates. Not even a buck converter is worth it. ( I will refrain from the referral to an anchor)

The rest is a cheat with software and the grid is happy.
240V 50Hz is very dumb device to emulate.

Two motors +/-  12 - 24V                           R 1800

All cut outs from Shcuurman Lazer Cut  R 1300
Galvanizing                                                  R   160
Bearings                                                       R   420
Gear                                                              R 1300

These prices are for one off's. My next order will be a set of 10 for my installation with two spare units.  That will have the true cost of this device.  The cheapest I could buy was R11K.
I can not buy sufficient solar panels at these costs for the Wattage. I might decide to get it from India or China as they sponsor our developments due to the devaluation of their currencies and SA simply to expensive.

I recon soon you will see a few of these mushrooms popping up as it has a national COC. Thus far I am keeping my inverter of the list but when I am a little more ready it will appear on that list of yours.
The court case of the COCT against me was in my favor now I can complete the job and hopefully start installing on a bigger scale in 2020. 

Nice to hear from you again.  And don't stop criting my stuff it is 100% worth every negative comment as it leads to improving the design and that is worth more than gold.


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1 hour ago, Erastus said:

If I do put a MPPT in between I loose another +/- 3% efficiency and the cost escalates. Not even a buck converter is worth it. ( I will refrain from the referral to an anchor)

I think we missed each other a lot in that conversation. The point is that to get the maximum power out of the panel you have to impedance match things. An MPPT is just one way of doing that. Anything that can vary the "Z" (usually in a closed control loop) in order to get optimal power is "technically" and "broadly speaking" an MPPT.

For me, who is restricted to 3.5kWp on my roof... all of this remains academic. And very fascinating.

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This product I am designing to make sure it is affordable and people can convert to solar as it is easy and cost effective.  The selling of it will start as soon as I am happy all calculations are correct.  I do not understand why a 10Kw grid tie inverter must cost R30 -  R55K. It is dumb electronics. So we will soon start shaking the trees. Neither do I understand why a 7Kw installation must cost R130K. The most expensive part the CPU $11.50.  The rest does not make sense.




Edited by Erastus
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H Gerrie,

The unit is capable of handling 24 panels. I will show you in the next set of photos how they are mounted.  The "neck" part is a 45mm bright bar shaft with additional what I call spacers that that creates a shaft of 85mm. The mounting section get screwed on that with a 24MM hi tensile bolt and 8 x 8mm 12.9  bolts.



This is what the frame looks like



Quotation from Shuurman for the lazer cut and steel:

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On 2019/10/02 at 6:22 AM, Erastus said:

REMEMBER I HAVE 0 mechanical experience so make suggestions please.

Hi Erastus

I’m sure there will be a bit of school fees along the way but it will be worth it at the end of the day. And the best way to learn something is to experience it first hand.🙂

The only thing I would suggest is get as much advise as possible on the mechanical wear and tear parts and try to determine where and when it will be subject to the most forces.

Just out of interest, I worked on a tower crane once and was told when the crane is not in use over a weekend, The top cross boom motor brakes must be released. So that when the wind is strong the wind can turn it in a position with the least drag to prevent damage to the crane.


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I started 2 years ago and tailored the system Maths calculations and stress design is not an issue. I got 2 companies involved that looked at the design and therefore I have 2 x COC for mounting and design. My electricity bill was between R3.5 - R4.5K a month. Its already worth it.  I installed a inverter and 8 panels 4 years ago at a cost of R36 000 (this included the solar tracker).  I changed my koi pond pump and swimming pool pump design and dropped the power usage. My KOI pond has 55 000 L and consume 90W per hour.

It has already paid for it.  What I am doing now is to streamline the design and cut out humans as much as possible in the manufacturing phase. I need to get 10 more units for my house therefore if I can cut out any human and use a tool I do it no problems.  Once cut  I need about 20cm of welding +/-  R90 other than that its done via machines. The reason why it took this long is I battled a court case with the COCT re my house for 4 years. Since it went in my favor I now do the modifications.  The final nonsense of the City Of Cape Town was resolved on Friday 13 September and then I started with the new installation parts and thought I will share as I go along should any one be interested.

I been off this site since Jan but thanks I do appreciate any comments. As for this design I live facing the North West directly off the sea. When it is stormy the gusts are tough and 4 years it with stood the test of time. Can't say the same about my house as two years ago I had R120K storm damage but the system was ok.  The beauty about a solar tracker is that one has to fight rust more than anything.  Wear is calculated @ RPM /Hr x Hr per Day X days per yer.  In this case we talk about 270deg  in 10 hours and then 270 deg in 5 minutes.  Roughly 1 rpm / 24 on the motor it is 260 RP per day. That is why I now have all parts galvanized and closed off against the West Coast weather. 

My only failure thus far was the motor during the heavy salt season in Cape Town.  Some day the salt is like 3 mm crystals on it and it destroyed the casing.  One bearing I lost as I forgot to fill it with grease.

The low RPM and low movement has other challenges but the maths nothing a calculator can't do.

Many thanks for the heads up.  Any more heads up will be appreciated.

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25 minutes ago, Centurionsolar said:

Hi @Erastus,


Well done on your tracker thus far!  It's a BIG mission, but ultimately worth it!


Here is a link to the one I built about 6 years ago. I was going to offer these frames commercially, but the effort, time and cost involved simply didn't make sense.  This was permutation number 4 to finally get it to work properly and track on both axis'.  I opted for a simple LED control consisting of 8 LED's with a little "roof" so that I measure the resistance through each LED, and the moment the little roof covered one of them, the resistance of that pair would change and the frame had to shift so that all LED's would measure the same again, at which point it was perpendicular to the sun again.

I also incorporated an anemometer to measure the wind speed, after which it would park, monitor for 30 minutes and then resume tracking once the wind is gone.  You will see that I tested just about every panel under the sun (quite literally, hahaha) to test their performance, how they age, etc, and after 5 years I redid the entire frame with new LG Neon2 panels, so it looks much nicer now...

I also had mine tested by a group of final year engineering students as part of their thesis, and they took samples of the building, etc.  They determined that it should in theory withstand wind speeds (when parked) of up to 207kmph, and when tilted a maximum speed of around 160kmph should be fine.   In both scenario's at that speed you'll have more to worry about than the panels on the roof...


Anyway, hope you can find some inspiration from it, and good luck with the rest of your frame!



Kind Regards





Baie nice. Look at the photo that is how the North Wester getting to us 100% directly. I looked at the size of your tubing looks +/- 20mm x 2mm is that correct?

i could not get a COC and the storm that hit us 2 years ago the gusts bend the 20 x 20 with the first set of gusts. Would love to see more re your motors etc. Once I post how the Y axis works you will understand my logic.

Many thanks for sharing this.  Did you use blue LED's?
Do you have the negative pressure of the top array of solar panels?



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The reason why I have this approached is I have a pan handle of +/- 40 meters with a 3 meter retaining wall. My neighbors are +/- 3M above me.  Therefore I am building a single garage (40M a 4M  :D )on top of the retaining wall for the solar panels. It is 8 meter wasted space. For your next question the reason for the garage is simple. National law states a solar panel can not be mounted higher than 1.5M of the mounted place.  Therefore I can build a garage with a 2.9M wall and then mount the panels on top of the garage. The bottom part is still used as a drive way to my house with a garage on top and the 4 meter unused land is then covered during the day by solar panels that acts like a shaded roof for the cars when they stand in the drive way. I am not allowed to have a roof or a shaded area on the drive way for the 4M section but the solar panel which will then be +/- 8 M above the drive way will work as a shaded area block the bulk of the sun.  Following the sun means I have a perfect shaded area.



Edited by Erastus
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