Solar Tracking

For a very small solar panel, you can use a pan tilt platform with servos, like this one: http://www.robotshop.com/en/lynxmotion-pan-and-tilt-kit-aluminium2.html

Or these: http://www.trossenrobotics.com/c/robot-turrets.aspx

It is easy to control servos, but you will need to do some math to figure out how altitude and azimuth relate to the pan tilt orientation.

jremington: For a very small solar panel, you can use a pan tilt platform with servos, like this one

Or these

And consume all your solar power driving the servos?

Thanks guys! These links are great.

Can you give me some direction on doing the math? The following turret has two servo motor one on the top and the other one is on the bottom. Both can move from 0 to 180 degree. But what angle they will be at the time of power up or start up.

Let's say the azimuth is 294 and Elevation Angle: 19 then which motor will follow the azimuth and which will follow elevation.

For example for the following motor

http://www.trossenrobotics.com/robotgeek-pantilt.aspx

erica

Servos know where they are. You command the servo to set its output arm at a particular angle (within an allowed range).

You will have to experiment to figure out what range of servo angles will work in your application.

And consume all your solar power driving the servos?

I don't think that is a concern right now and besides, a 1 W solar panel can't run an ordinary servo anyway. The OP has a lot to learn, and needs to start somewhere.

So the servo can not move to 294 because according to the data sheet of he turret the maximum angle the servo can move to is 180 degree.

It seems like that the top motor will be used to follow motor's elevation and the bottom motor will follow azimuth. Am I right?

erica

You can buy servos with an angular range of greater than 180 degrees, if you need it.

There are lots of different types of pan/tilt platforms, so spend some time shopping and pick one with the range you need. Here is a good selection: https://www.servocity.com/html/pan_tilt_roll___accessories.html

Equatorial mount far simpler.

Just sayin ... :roll_eyes:

Agreed. Either a pan or a tilt platform could be used in an equatorial mount arrangement.

Hi,

1) Azimuth: 360 degrees per 24 hours = 15 deg/hr = 0.25 deg/min. SO, do I need a servo motor that can do 0.25 degree minimum. Am I right?

Elevation: 180 degree per 24 hour = 7.5 degree/hr = 0.125 deg/min. So, do I need servo motor that can do 0.125 degree minimum. Am I right?

The servo motors mentioned at the following link does not discuss the specifications of the servomotors in degrees. I am wondering do I need a servo motor or stepper motor. or How can I make the servo motor move in degrees?

http://www.trossenrobotics.com/c/robot-turrets.aspx

erica

Well, the point is that unless you are using it for an astronomical observatory, for an equatorial mount you only need it move it in steps of ten degrees or so, possibly more finely if you are using it for a solar furnace. This means you only need move it every forty minutes.

What you need is a large gearing ratio such that the stepper motor will not move when not powered. A common (hobby) servo will not stay put (especially when there is wind shear on the assembly) and will tend to use power to keep itself in place. A common stepper will also require power to stay in position but with appropriate gearing may be powered up only to make individual movements. You really need a stepper and high gearing of the sort that you would of course find in a clock (running at half speed).

In general, this requires something purpose-built.

Hi,

How about the following dual axis AC motor

http://www.dwgdistribution.com/ecommerce/pc/viewPrd.asp?idproduct=1635#

What does Pan speed : 6 degree / sec, Tilt speed: 3 degree/ sec mean? Can it do the job? I meant I need 15 degrees / hour movement to follow the sun. How can I design my PWM algorithm keeping in mind this motor?

Plus I was reading the following paper

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3658738/pdf/sensors-13-03157.pdf

It says on page 3162 , Figure 5 that a cylinder was used to create the shadow. Can you guess the dimension of this cylinder?

Erica

6 degree / sec mean that this device is able to move in pan direction by 6 degrees in one second,12 in two seconds and so on…
I don’t know if this motor is ok or not because it depends on the dimension and weight of your panel.

In figure8 there is a photo of this device. I guess it is tall about 15cm and the diameter is about 5-6 cm. it seems that they are using the same motor,

maybe you can get some ideas here

I did something similar, a dual-axis sun tracker using light sensors:

|500x400

Details, video and Arduino source code are posted on my blog:

http://www.janspace.com/b2evolution/arduino.php/2014/07/13/mobile-sun-tracking-solar-power-plant

Hope this helps.