Dual axis solar tracker
ajit.nayak87
Posts: 76
Dear all,
I am trying to do dual axis tracker . Let me know following list of formula envolved for calculation, algorithms
component used RTC-DS1307,inclinometer, arduino mega, LCD keypad
I am trying to do dual axis tracker . Let me know following list of formula envolved for calculation, algorithms
component used RTC-DS1307,inclinometer, arduino mega, LCD keypad
Comments
And judging from his other thread, he's also making it more difficult for himself by using linear actuators.
(Nothing against linears, personally, they're just not the right tool for something that rotates With an even motion)
Or if you want to use a Propeller see Solar Position Calculator & Almanac by Prophead100 in the OBEX.
What are you tracking?
PV Panels? If so take a look at the Tripod Mounts which are "Polar Axis" and only need single axis movement.
Something more interesting like a Parabolic Trough or Dish concentrator?
Or something hard to do such as a Heliostat.
You have to describe your project in more detail.
Duane J
Not quite accurate. You could use a polar mount and get close but you really need 2DOF to track the sun.
On paper, actively tracking DEClination can add about 7% more energy per year than with a fixed mount.
However, by manually setting DEClination 4 times per year you can get about 5%/year.
The great majority of energy increase per year is gotten by simply actively tracking Right ASCension, the daily motion of the sun. Depending on the location this is often greater than 70% increase over a fixed mount.
My customer at the south pole would get 280% over a fixed panel which would make little sense.
Of course if your using a dish concentrator dual axis is often required unless the concentration ratio is very small.
Duane J
Easily adaptable to most other languages.
1) http://www.powerfromthesun.net/book.html My object uses these formulas and is cross referenced to the equations on the site. The website and object also have heliostat formulas. The object has a linear actuator formula too.
2) http://stjarnhimlen.se/comp/tutorial.html (references are not in spin but very useful)
3) http://obex.parallax.com/search/solar The SPIN object is here and a higher precision C program in the auxillary file that could be adapted. A local highschool STEM program locally uses a version of the SPIN object for senior projects which may be similar to what is needed.
In case others haven't been following along, here's a link to the other thread.
As mentioned numerous times in the other thread, the motion of the linear actuator will depend on the geometry of the system.
I encourage others to take a look at the other thread before spending much time offering formulas here.
Very true Duane, which is why I said "not quite accurate". For a flat panel the extra 7% is not usually worth the extra complexity.
1) when Does tracker will move in horizontal and vertical direction???
2) I am using NREL codehttp://rredc.nrel.gov/solar/codesandalgorithms/spa/ from this link with accuracy of +/-0.003 degree. Here i calculate elevation and azimuth angle for with time. How can use altitude ,azimuth and elevation angle to calculate select position of sun???
3)flowchart algorithm for implementing dual axis tracker.
4) I am using below sensor for determine actual position of trackerhttp://www.leveldevelopments.com/products/inclinometers/inclinometer-sensors/das-90-a-inclinometer-sensor-dual-axis-90-0-5-4-5v-out-7-35v-in/ as feedback sensor.
I Google it all doing using LDR and based on assumption angle calculating Sunpos angle.
Of course there is no point in following the sun when it's below the horizon! You know when and where the sun will rise in the morning so just "rewind" to that starting position last thing at night.
2) I don't understand. That algorithm gives you altitude and azimuth of the sun from your position at your time. That is "position of the sun" relative to you.
3) No chance. You probably want to make a start on your own design and code. Then other may be willing to comment on it.
4) Sounds nice. Why do you need it? If your installation is fixed to the ground there must be cheaper ways to tell the position/orientation of the moving parts with respect the ground.
ya . I wanted to code my own. I have some logic in my mind to getting started is problem for me. I wanted to which angle i need to consider to calculate sun position for dual axis tracker.
From altitude and azimuth how you calculate sun position??
Why all goes with dual axis tracker ?? why dual axis two axis of rotation??
I don't understand the questions.
A conventional DC motor, with motion feedback is powerful and one valid solution. Either optical or magnetic quadrature is available for feedback. And H-bridge is required to drive the motor in two directions. But these motors perform best at high rpm. They are not really made for stop/start and holding a position. Brushes may wear out quickly with stop and start loads.
A stepper motor with a stepper motor driver and power supply can be easily bought as a package on EBay and will do the solar tracking. A 4amp rated stepper at 24 volts would be 96 watts, over 1/10th of a horsepower when comparing watts. And it is intended mostly for holding power rather than requiring .
I would go with a stepper motor package. It may be a bit hard to find only a 2 axis deal. You might get 3 axis with some extras for the same money. Here is an example, but you can shop for a better price and better fit.
Where is the power for the solar tracker coming from? Household 120VAC or a battery supply. You can eliminate the power supply and just buy the motors and stepper controllers if it is a battery supply.
http://www.ebay.com/itm/CNC-3-Axis-Driver-Breakout-board-2N-m-Stepper-Motor-285oz-power-supply-kit-/280832618337?pt=LH_DefaultDomain_0&hash=item4162edaf61
1)Selection of worm gear boxes. what are points it included for selection.
2) selection of motor like linear actuator, stepper motor, dc motor, servo motor etc
3)motor Driver and current carrying selection.
4)current carrying capacity of motor with/without load
5) gear ratio calculation for determine speed of worm gear and motor .
6)torque calculation steps for worm gear boxes.
I thought we were just doing a homework exercise.
And as I said before.. where is the electricity coming from? AC mains or is this a battery powered device being charged by the solar panel?
Do you remember this? I was thinking direct drive stepper motors. Or maybe a set of reduction gears at best. I still don't understand why you throw a right angle in and require worm gears.
I would do this by pulling on it with a string, or if it's big enough a rope. In line with the rope you will have a linear spring balance that will tell you how much force you are applying.
Next you need to measure the distance from the axis of rotation that the rope is tied to.
With those force and radius measurements you can calculate the amount of torque you are applying to the structure when pulling on the rope to get it moving nicely. Note that it may take more force to start it moving than to keep it moving due to stiction.
With that information in hand you can start to think about motors, the torque they are required to produce, the speed they will run at and any gearing required.
Years ago we did this for a huge parabolic radio astronomy dish that needed a new turning mechanism. Me and two other guys pulling on the rope. Our professor watching the spring balance and recording the force measurements.
Let us know how you get on.
Nice pragmatic real solution. Of course, that assumes the solar panel or whatever is already built.
I have been thinking a lot about solar tracking interms of controlling light penetration (for heat build up) here in southern Taiwan. Having windows that let in indirect light while avoiding the heat gain of direct solar rays is another application for this kind of project.
And it may just signficantly reduce the loading of air conditioning during daytime hours while allowing for natural lighting and at least some directional view out of south facing windows.
1. Forget about 'dual axis' control.
What you need to start with is an axis that's aligned with the Earth's axis(take a look at motorized satellite dishes).
Then you need to rotate the panel around that axis. A stepper motor is GOOD for this. Pick up a geared one if you want really, really high accuracy and a bit more holding power without using too much Amps.
Here's a fun fact: The sun moves 15 degrees across the sky every Hour. Yes! it's a CONSTANT!
That translates to 1 degree every 4 minutes. On the dot.
This means that if you know which time the sun rises over the horizon, you also knows WHERE it rises.
So that the solar panel can be placed in the correct position as soon as the sun drops below the horizon in the evening.
Use cogs to transfer power, and you won't have to mess with calculating from linear to circular motion.
That just leaves adjusting elevation... Which probably only needs adjusting every few days or so, as long as the axis was set properly to begin with.
That can probably also be calculated and a simple table set up based on how far North or South you live.
A vertical mount(or horisontal if you happen to live near the Equator) and dual axis motion is not only incredibly wasteful but also overly complicated so unless this is going to be a mobile system, please bury that design wherever they buried all those 'ET the Game' game cartridges.
In other words, eliminating half the motors also reduces the overall cost in a significant manner.
When I took my license exam for engineering they did have a section on test called "Engineering Economics". It just seems that if you are not including the overall cost analysis into your design, you are not ready to become a real engineer.
Good support with ball-bearing pivot points would likely enable you to use a smaller motor as well. But I doubt this will ever get built as the original poster seems to have some very unclear goals.
He recommended plastic bearings are the best as no lubrication is needed, other than the plastic itself.
Second place is Oilite type bearings.
And an unusual bearing type is oak wood that has been boiled in paraffin wax. Yes this is old technology but I have found this works nicely.
A nice tracking mount type is what I call "Tripod Tracking Mounts".
This is the future of tracking mounts.
Check out the ones at Nellis Air Force Base.
Duane J
How right you are.
Back in the 70's oil crisis solar power was all the rage for a while. In my technical school some architecture students built a huge parabolic reflector that tracked the sun to heat water in a tube at the focus.
The "gear" that drove this was a semicircle of plywood. The motor that drove it was an old wind up clock mechanism. Just turn it back to the right direction in the morning and wind it up, good to go all day.
VDish1
Of course, this used a permanent magnet DC motor and a solar tracker.
or
This NotASprocket.
I call this a NotASprocket because, although it is driven with roller chain, it doesn't need teeth as the chain is bolted to the pulley. Unlike a normal sprocket, solar trackers don't need to turn all the way around so it is permitted to fix the chain to the pulley so it can't slip.
Duane J
Something like that. It was a long time ago, I don't recall exactly. I do remember being impressed by how amazing simple and cheap it was.
The stuff on those pages you linked to petty much has this thread project covered I'm sure.
Got real serious in about 1995 and started Red Rock Energy, pretty much a hobby that went NUTS.
I post about things with which I'm interested. Hopefully others also find them interesting too! My site is not exactly written as a public page. It's more like a convenient record of the things I have researched and done. A lot of people have bounced off the things I have started. And this is gratifying to me!
Not to brag, but, I consider myself to be nearly an expert in the field of Solar Tracking. I have studied all aspects of the field.
Duane J
I have asked the questions like:
1) if worm gear be selected, how torque generated been calculated for selecting dual axis tracker.
2)with worm gear , which motor perform better like BLDc, Servo, Stepper etc
3)Design steps of dual axis tracker