DIY Solar Tracker

Starting with the building of a solar tracker.




The tracker is of Az-El type. Both the Azimuthal and Altitude movements are to be effected using a common satellite dish actuator shown in the photo above. I already own one which will be used for the Azimuthal movement. A small model using wood was prepared and the actuator tested. The movement was nearly 160 degrees, which I think should be adequate for our latitude, to track the sun from east to west.

The second photo is just for perspective so one can have a feel of the size of the actuator.




The photo below is of two bearings to be used on the tracker. The one on the left is a thrust bearing which will carry the full load of the 4x 200 watt panels and mounting hardware. This is estimated to be around 220 kgs. Cost of the bearing was Rs. 700.

The bearing on the right is a support bearing for the 50 mm shaft. It cost Rs. 450.

Also purchased a 50 mm dia steel bar for the shaft of about 15 inches length. Got it at Rs. 89/kg which worked out to Rs. 570.

Tomorrow the machining of the unit starts inshallah. Should take about two days.

Will post pics of completed unit.

Aurangzeb



Machining of the bearing unit completed. Photos of the unit soon.

Since the bearing is quite robust I am re-thinking the design of the tracker to take up 8 x 250Watt panels. Initially only 4 will be installed for 1KW. Four more later to bring the capacity to 2 KW.

Aurangzeb

Machining of the bearing unit completed. Photos of the unit soon.

Since the bearing is quite robust I am re-thinking the design of the tracker to take up 8 x 250Watt panels. Initially only 4 will be installed for 1KW. Four more later to bring the capacity to 2 KW.

Aurangzeb

Wow...

That car needs to be washed seriously :o

1 Like

Yes it certainly does.

It is the main support vehicle for coming and going to our under construction farm house. The last 200-300 meters to the land are katcha. This is the result of visits after the recent rains when everything was mud mud and mud.

So just waiting for the rainy season to go away before it goes to the service station :-).

Aurangzeb

my wild guess that is KIA sportage or Daihatsu Trios

Kia

diesel or petrol?

3SFE petrol.

tough little SUV isn't it? long cabin version good for single family

COMBO BREAKER...!!!!!!

@ Mr Aurangzeb

so while the bearings seem adequate to bear the load, do you think the steel shaft of 5mm is enough for 4x 200 panels?..

also what is the base assembly for such heavy design.. a few of these can certainly be mounted on a house roof?. too much weight on a single shaft?

[quote=“farhan_ds, post:11, topic:21963”]

COMBO BREAKER...!!!!!!

@ Mr Aurangzeb

so while the bearings seem adequate to bear the load, do you think the steel shaft of 5mm is enough for 4x 200 panels?..

also what is the base assembly for such heavy design.. a few of these can certainly be mounted on a house roof?. too much weight on a single shaft?

[/quote]

Thanks for bringing the thread back on topic.

It is 50 mm and not 5 mm. 5 mm is obviously too weak. And I am now planning for 8 x 250 - with 4 to be installed in the first phase.

Your observations are exactly what I am faced with at this point. It is also my first experience and so I want to be very conservative given the fact that over two lakhs worth of panels would be hung up and dependent on the mounting.

When I looked at the Net to glean ideas I found that the most used format is a single steel column in the middle. This format is inherently less stable than one which is supported at both ends. Additionally it would require even heavier structural elements (columns beams etc.). My own starting point was two support columns at both ends which is inherently more stable and can be built using ordinary material available on shops making metal doors and windows thus making it cost effective. An 8 panel structure can be built in a manner that 4 panels are located on either side of the central axis. This balances the weights and thus the unit can be adjusted manually for seasonal changes of the path of the sun.

I believe the preference for singular support column stems from the lack of real estate available to the ordinary Joe living in the West.

At the base I plan to put 3 feet long channel sections in the the shape of a + . The bearing will be bolted at the center of the +. This will help to distribute the load over a 9 sq foot area.

Aurangzeb

Base unit completed. Weighs 50 kg. The plate mounted on the shaft rotates and will provide the platform for the mounting hardware of the 8x250W solar panels.

Over the coming weekend I hope to be able to design and fabricate the mounting framework.

Will start the Arduino based solar tracker unit after that.

Aurangzeb

that seems much more durable..indeed the problem of space for small apartment dwellers and 3 marla houses in west would have been the reason for such single shaft designs.

but again, 2x 50kg bases, plus almost 15kg panels x8, plus the wight of the frame fitting for 8 panels almost another 50kg (roughly)..that would be almost 300kg per 9 sq foot.. isnt that load too much for a roof to bear in such a short span of 9 sq ft?.. wouldnt there be roof settling? are you planning for any concrete reinforcement or additional garter? why is that fanta filled upto the cap? is that base unit custom built or ready made? (seems custom built) how high / long will be the shaft for panels mount?

Not two but only one 50 kg base unit will be used in my design.

Yes, the weight issue is there. However the prevalent design of the roof slab of our urban houses can easily withstand this kind of load. However it would certainly be prudent to install something like this over a beam or a column in an existing building. I have the option of installing it on ground as I have space available. For others particularly urban dwellers this option may not be available.

The Fanta is just for perspective so that the viewer can get an idea about the size from the photo. Incidently the bottle is filled with motor gasoline for cleaning a tough stain on a table cover that refuses to go away using conventional cleaning :-)

The height of the shaft will depend upon the size, particularly the width of the panel. I have looked at Yingli and Akhtar Solar panel sizes. Yingli is 990 mm wide while Akhtar is 550 mm. Therefore say if I decide to use Akhtar then the shaft height would be 2x550=1100 mm. Add another 50mm for clearance from the base, for rotation, and you have 1150mm. Add the height of the base rotation unit (440mm) and you have 1590mm. That makes it about 5 feet above the roof/ground level. This is a reasonable height resulting in a stable structure one which one can work easily while standing on the ground without using ghori or table.

The width would be equal to 2xlength of panel. Again taking Akhtar case it comes out to be 2x1560mm which is 3120mm or just over 3 meters. So the turning radius is about 1500mm.

Aurangzeb

i am extremely extremely interested in how this is gonna work out.. its an ambitious plan and the base work has been theoretically solid uptill now. i do hope this mechanical excersize is fruitful and stable in long term..

the 2 shaft bases were for 2 panels setup.. ie you said you were going for 2 sets of panels on 2 frames..so 1 base for each.

at 5 ft height is from the lower end or the mid of shaft joining frame or the peak height border of the frame.?

have you taken into account that such a huge frame on a single shaft is extremely unstable even when supported by columns on each end? the sheer momentum even in mild breze or medium wind will be stressful on the structure, toppling it on side.. as wind can blow in any direction not just left to right.

also are you going to bury the base in the rood with chips or cement or is it just going to lie on roof openly?

Yes, I have plans to build 2 of these for two seperate arrays.

The 5 ft. height is to the mid of the shaft joining the frame. This shaft will be horizontal and hold the panel frame. It will rotate along the horizontal axis thus compensating for the seasonal movement of the sun.

Yes wind is the main design risk for this structure. During Aandhi the force of the wind can exceed 25 pounds per square inch. Here we would have more than 16 meter square of area. Therefore the force will be formidable. That is the reason I have used 1 inch thick steel plates in the design of the base unit. Similarly strong and heavy members would be used in the structure to make it real sturdy.

I plan to mount it on the garage roof which is a 5 inch thick slab of RCC. I have specifically added platforms in the design to accomodate these arrays. Alternatively I also have the option of mounting these on the ground. This will require a 3 feet x 3 feet hole about 2 feet deep for the foundation.

Design of such arrays and its structural elements is a straight forward engineering calculation. You can find many papers for it on the net. While building such a system has it complications, both during construction and later during operation, it is more efficient and can yeild upto 30-40% more energy. I would like to reap these gains which would probably not be possible for the ordinary non-technical person.

Aurangzeb

[quote=", post:, topic:"]

I would like to reap these gains which would probably not be possible for the ordinary non-technical person.

[/quote]

Indeed, and only by such feats of Your hard work and dedicated engineering, comon people may be able to reap rewards effortlessly when it all goes commercial.. kudos to pioneers..

just asking though, wouldnt it be easier / stronger / safer / only slightly more expensive to use 4 panels per frame instead of 8 panels?

It would certainly be. The force exerted by the wind would be immediatly halved due to reduction in the area.

However the cost of the base unit with its actuator and electronics etc. will be divided over half the output power. The two main cost centers of the design are the base unit as well as the actuator. These remain fixed. Infact we thought hard about how to reduce cost of the base unit and could only come up with a reduction of about Rs. 800 in material and 500 in labour in a cost of just over Rs. 10K. As I am sure you can see from the simplicity of the design, there is no space to cut cost. The only thing we could think of was to use half inch plate instead of 1 inch which is neither here nor there.

The reduction in cost in using a chinese actuator would also be negligible. I don’t know what an actuator costs these days but if you have to drive both azimuth and altitude automatically then cost of these actuators is likely to exceed 10K.

So there you have it. As you reduce the number of panels the two fixed costs mentioned above will start becoming not only significant but making the project unviable. As they say Darrhi say moochain lambi hoo jaain gi :slight_smile:

Aurangzeb

HAaaaaah :D