Solar heating with motorized satellite dish

Greetings every one,

Let me Introduce my self,

My name is Igor Stojanovi? and for a while I am member of arduino society.

Great potential of open source world in my opinion.
That's why I joined you.

With help of this forum and use of internet I planed,and constructed my random moving target for airsoft gun.
I had noticed that there was no such thing to find on internet

Following features are implemented:
Start, stop and count reset over IR remote control.
4 digits 7 segment display module, for score counting.
Using piezo siren as shock sensor mounted on target.

Pretty impressive for absolute beginner.
Big shout to you for your help.

I am more than willing to provide source code for arduino programing and sketches in Solidworks format.

Hope that someone will have fun with it as I had :slight_smile:

Here I am again in front of you asking for a help with a new project that does not exist in this world.
Especially not in this form.

Idea is not new:

This one wants his bear warm, he must be British :slight_smile:

Joke on the side, energy is day today more expensive.

Using inexpensive satellite dish as parabolic mirror it is possible to accumulate serious heat in focal point,
Placing black metal object can easily create heat and over 200 degrees ( Celsius ).

This is serious potential even for cooking.
Not to mention warming up homes in winter days.

Biggest drawback of this system was that motorized heads capable of caring bigger dishes were very expensive
That discouraged lots of people ( money is tight everywhere)

Here Arduino comes to the rescue.

New inexpensive models are here.
But with a catch.
This units are controlled over signal in coax cable.
Here is goal :
HOW TO, BY CONTROLLING TWO STEP MOTORS OVER COAX CABLE WE ARCHIVE REAL TIME TRACKING OF A SUN MOVEMENT OVER THE SKY?
In winter days, sunny day is very short, there fore best possible sunlight absorption.

If any of you can point me if which direction,
I will be more than grateful :slight_smile:
I want to create easy to install, sun tracking parabolic mirror heater to help people and make this world cleaner. :slight_smile:

The problem is that these motor's only track in. One dimension in the sky, the oath of the ecliptic where all geostationary satalites are. To track the sun you need control in azimuth and elevation which you do not have with these systems.

Very much, and quite painfully aware of that fact my brother :slight_smile:
Looking to find way around it.

Signals for movement of motors are send through coax cable... how to tap in? :slight_smile:

Need datasheet on stepper motor powered satelite dish.
What fo you mean by " through coax cable" ?
It sounds like yiu mean 75 ohm RF COAX (like TV antenna cable)
If so , then signal is " piggybacked" over satelite signal cominv from dish. I've heard of this long time ago but have no details,
Do you ?
As already mentioned you are " short" one axis.
You need a sky- tracker telescope star tracking system adspted for satelite dish.

It works like this

The business of pointing a satellite dish at the sun is exactly the same as pointing a solar panel at the sun - except that the satellite dish might need greater accuracy - i.e. adjust position more often. There are several Threads about aligning solar panels.

If the dish rotates about an axis aligned to the sun (the up/down axis - elevation? - sorry, can't remember the technical term) that axis only needs to be adjusted occasionally as the seasons progress. The left/right axis needs to be constantly adjusted throughout the day. If the dish does not rotate about a sun-aligned axis then both up/down and left/right need to be adjusted throughout the day.

The biggest problem is likely to be designing a mechanical system that can resist wind forces. Use of a DC motor with a worm drive has a lot to recommend it. The worm drive prevents forces on the dish from moving the motor.

I don't see any role for stepper motors as they are very inefficient and will probably consume more power than is captured from the sun.

Two pairs of Light Dependent Resistors and 20 or 30 lines of Arduino code should be quite adequate for feedback to control the position of the dish.

...R

If the dish rotates about an axis aligned to the sun (the up/down axis - elevation? - sorry, can't remember the technical term) that axis only needs to be adjusted occasionally as the seasons progress.

Given that the sun subtends an angle of about half a degree, and that the average satellite dish is about 15 degrees then I would suggest that the elevation would need to be changed at least once a week.

The pattern the sun makes in the sky as the year progresses is called the analemma, there are some great images of it on the net, here is one such site.

Have you tried to google solar oven.

Firstly I want to thank you all for your posts, ideas and suggestions.

Had small debate on other places as well.

Robin2
Seems that your approach using Light Dependent Resistors gains popularity.
I must admin that is much more down to earth method which does not ads up on overall cost of project.

I am currently on the search for dissent DC motors with worm drive.
Seems with this approach using Light Dependent Resistors and 2 DC motors it is possible to achieve full tracking of sun.
Experiments are to follow :slight_smile:
But first I need to learn all there is about Light Dependent Resistors.
Regarding sample code, Any pointers in which direction I should look?

websonic:
I am currently on the search for dissent DC motors with worm drive.

Used car windscreen wiper motors are readily available and powerful.

I have also seen a system where the solar panels are moved using a screwed rod connected to the motor to drive a nut forward or back along the screwed rod. This does not allow as much angular movement but would be perfectly OK for the up/down movement of the dish.

Seems with this approach using Light Dependent Resistors and 2 DC motors it is possible to achieve full tracking of sun.
Experiments are to follow :slight_smile:
But first I need to learn all there is about Light Dependent Resistors.
Regarding sample code, Any pointers in which direction I should look?

Connect an LDR with a regular resistor to make a voltage divider and read the voltage at the junction with analogRead()

Arduino 5v -------LDR-------Resistor ------------Arduino GND
|
|
Arduino analog pin

You will need to experiment to find suitable values. For the movement of the dish the important thing is the difference in value between two LDR readings - not the absolute value which will vary widely as the strength of sunlight varies.

...R

The problem is that these motor's only track in. One dimension in the sky, the oath of the ecliptic where all geostationary satalites are.

That doesn't look correct to me. The geostationary satellites are in an orbit direct above the equator of the earth. The apparent path of the sun (the "ecliptic" ) is not directly above the equator, it is tilted relative to the equator by about 23 degrees, that's why there are seasons.

There is nothing wrong with what you say, but also there is nothing wrong with what I say.

A satellite tracking motor is designed to sweep the path of the celestial equator. It is a single motor that will point to all the elevations of the celestial equator. The sun does not follow the path of the celestial equator and therefore can not be tracked with a satellite tracking motor.

Grumpy_Mike:
The sun does not follow the path of the celestial equator and therefore can not be tracked with a satellite tracking motor.

Maybe I am missing something simple ... wouldn't a satellite tracking system follow the sun if the pivot axis of the satellite dish is appropriately aligned. Obviously it will be slightly different every day.

If I am right it might be easier to make a DIY tilt correction system (i.e. the occasional up/down adjustment) rather than the continuous left/right adjustment.

However, if the satellite motor uses energy all the time that rules it out straight away for solar energy capture. A system that only uses energy for brief intervals while the dish is realigned is essential.

...R

One point, a parobolic mirror focusses at a point.

A cooking pot is somewhat larger so absolute pointing accuracy is not needed for that purpose.

If you can get the mechanics sorted, the simplest method would probably to use a clock to track the sun with possibly a manual adjustment for seasonal variation.

Telescopic aerial actuators are cheap, and only use power when working,
If the thinner top elements are epoxied in place, they are fairly strong over a more limited range.

wouldn't a satellite tracking system follow the sun if the pivot axis of the satellite dish is appropriately aligned. Obviously it will be slightly different every day.

Yes that is correct.

But that alignment is not easily adjustable on satellite mounting equipment.

Whatever the temperature at the focal point the total energy available is limited by the dish size and incident radiation.

Unless you have an enormous dish getting useful energy for space heating is unlikley.

Its an expensive way of doing it.

Parabolic trough collectors would be more economic, they are normaly only tracked in one direction as their design takes care of seasonal variation if orientated correctly.

Reflectors can be constructed from inexpensive materials also.

Collector being plumbing tube.

I have seen one of those tubes used without a mirror on a sunny uk day.

It boiled on its own without a mirror.

Used as the tea kettle on the day

Can i ask if you already have a mount.

They are not particularly cheap,
there are cheap and simple ways to do this already thought out in the solar forums.

By all means use an arduino to control , but if your real need is to get useful heat at lowest cost a dish is not the way to go.
Even if you have one already.

Boiling beer demodstrates the concept but using a dish is a bit of a gimmic.

Grumpy_Mike:

wouldn't a satellite tracking system follow the sun if the pivot axis of the satellite dish is appropriately aligned. Obviously it will be slightly different every day.

Yes that is correct.

But that alignment is not easily adjustable on satellite mounting equipment.

I had assumed that the entire mounting system would itself be mounted on a another mount that could be tilted.

...R

I visualized idea with LDR sensors in this rather primitive drawing using Power point.

Theory.
2 motors are used for lets just put Pan and Tilt.
4 sensor in 2 pairs are installed on satellite dish.
Size of focal point should be 1/3 or 1/2 of collector Height

Idea behind.
So presumably this would allow some extra time to pass before sensors must re adjust sun focal point to be in a middle of sun collector.

Lets just say for a sake of the argument that code, which says that sensors are activated every 10 minutes is implemented
Some electricity saving would be achieved right?
Implementing potentiometer we can even fine tune time interval of sensors activity.