Lets just say for a sake of the argument that code, which says that sensors are activated every 10 minutes is implemented
The sun moves at 0.25 degree per minute. It subtends an angle of 0.5 degree, therefore the sun will drift right across the focal point in two minutes.
That lives us with one electric motor activated just for short period, every 3 to 4 minutes, would you agree Mike?
This is theory of course...
This is Do it your self project mind you.
Size of the motors are again depending how big dish one wants to use.
Choosing right kind of motors depending in which country you are will live you with some mathematical equation
how big solar panel one should need to run it properly.
At this moment, I think that we should focus on designing code for LDR sensors, and later on output part of the code.
Do you generally find this agreeable?
Boardburner2:
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 normally 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.
Hi Boardburner2
To make efficient system you need those long vacuum tubes.
This solution is very officiant I would agree,
But, here is problem, They are very expensive and not readily available everywhere.
Finding those tubes cheaply would be big leap forward.
Unfortunately that is not the case, well at least for now.
I spent 2 month searching for cheap suppler, In Swittzerland, Germanu, Austrija and Balkans... no luck 
websonic:
That lives us with one electric motor activated just for short period, every 3 to 4 minutes, would you agree Mike?This is theory of course...
This is Do it your self project mind you.
Size of the motors are again depending how big dish one wants to use.
Choosing right kind of motors depending in which country you are will live you with some mathematical equation
how big solar panel one should need to run it properly.At this moment, I think that we should focus on designing code for LDR sensors, and later on output part of the code.
Do you generally find this agreeable?
This sounds about right.
The LDRs don't need to be far from each other but there needs to be a screen between them so the sun causes a shadow on one unless they both point directly at the sun.
I wonder if there is a risk that you are confusing temperature with energy. It is easy to get a very high temperature in a small amount of material but that does not need much energy. To be useful you need a lot of energy which implies a large dish and an effective way of making use of the heat energy - perhaps with a fluid circuit (water?) to draw the heat away to where it can be used. If a circulation pump is needed the energy economics may collapse.
I think I would see what energy could be harvested using a manually oriented dish (for 30 minutes, say) before deciding to invest time, effort and money in a motion system that might consume more energy than can be harvested from the sun.
I suspect solar heating has huge economies of scale just like wind turbines.
...R
Robin 2
To clarify:
Solar energy is transferred via parabolic mirror to focal point where is achieved high temperature.
Creating heat energy is dependent on 4 things:
Position of the mirror.
Amount of sunlight.
Size of the dish.
Time length of exposure to sun light
I agree that amount of heat energy is questionable here.
But there are ways of improving it.
Connecting 2 , 3 or more mirrors in series with pipe and using water as medium one can achieve 90 degrees Celsius of the medium.
There are primitive but officiant ways of accumulation of this heat energy during day light and exploiting it over night (for example).
You remember TA electric heaters?
They use to be popular 30 years ago...
Basically pile of bricks in a box use to accumulate heat energy over night when electricity was cheaper ( in some countries)
websonic:
To clarify:
...SNIP....
I agree that amount of heat energy is questionable here.
I understand the principle. I just wanted to raise the concern that the amount of solar energy captured might not exceed the value of the electrical energy needed to drive the system.
...R
Robin 2.
That is already had done,
In not perfect condition I might add.
Guys from Canada did raise temperature of air 40 Degrees Celsius (measured directly in wind pipe of solar collector)
They achieved this with aprox. 3 sqare meters DIY pasive solar colector, Just natural flow of air.
Perfect for warming your home during the winter day.
Could not find that specific video any more, Here is one very similar:
My opinion is that there is a problem.
But not in amount of sunlight available during winter days.
Even when hitting black surface, lots of sunlight is reflected, Just take look at any video of parabolic mirror experiments. and you will notice that object is so bright that's very hard to look at it.
Thats sunlight which escapes.
Trapping it will incise efficiency, no doubt about it.
And we are currently working on it.
Just for fun, greetings from Lithuania
This one is pure simplicity which one has to admire 
Energy return.
You will also have to consider the circulating pump that will have to run continuously during the day.
Assuming a delta t of 3 degrees.
You need to keep the collector temperature below 22 degrees for space heating or 55 for water heating.
Tubes in video are not needed except for one application which is a still.
In use they never boil.
Those tubes are light and desinged for roof mounting, they do not need a reflector as they are self steering
Using a steered mirror a simple pipe will do.
I have seen one demonstrated with a pressurised system got hot enough to melt the solder joints and explode with superheated steam.
This is typically what happens with focussed systems when the pump fails.
I think that using a collector to heat a pile of bricks is a dead duck without a very large collector, 5 sq m min.
As the temp increases the losses increase dramatically, solar heating is designed for minimum temp not max.
Iv been thinking for a bit on this and i would suggest you get your temp sensors and pump sorted out before you look at steering mechanisms, as without it your system will not work.
Boardburner2:
Iv been thinking for a bit on this and i would suggest you get your temp sensors and pump sorted out before you look at steering mechanisms, as without it your system will not work.
That's, easy part.
Control and safety-limit thermostat with a capillary tube (3-pole) gives you nice option of 3 times NO and 3 times NC contacts.
Stooping or starting pump on desired temperature values.
Can be used even for analog input on arduino it self. (Pump not working, if high, go pane maximum left)
And for pumps,now days there is wide range of water and oil pumps for reasonable price.
websonic:
Boardburner2:
Iv been thinking for a bit on this and i would suggest you get your temp sensors and pump sorted out before you look at steering mechanisms, as without it your system will not work.That's, easy part.
Control and safety-limit thermostat with a capillary tube (3-pole) gives you nice option of 3 times NO and 3 times NC contacts.
Stooping or starting pump on desired temperature values.
Can be used even for analog input on arduino it self. (Pump not working, if high, go pane maximum left)And for pumps,now days there is wide range of water and oil pumps for reasonable price.
NO.
You need a speed controllable pump and at least two temperatute sensors.
Household type circulating pumps can be had specificaly for pwm speed control between 30 to 100%
Its not a case of having fixet thermostats as the delta t has to be dynamically tracked..
Example if your water tank is at 35 deg c then the pump runs until the collector drops to 38 deg c.
When the tank gets to required temperature then a heat dump loop is required to avoid collector overheating.
An electrical divert valve is needed for that, however in your case it may be sufficient to move the dish off focus.
Dont forget this system can work both directions so if the sun goes in and the pump continues it will cool rather than heat
As an aside to that, solar ovens can be used at night as a refrigerator.
With an ambient temp of 10 deg they can make ice.
The tracking problem is trivial compared to getting the circulation right.
websonic:
Robin 2.
That is already had done,
...SNIP....
I feel I have been misunderstood again.
I am not saying I think there is a problem. All I am saying is that if it was my project I would do some measurements of energy capture before committing to the project to ensure that I wouldn't be disappointed.
I would be delighted to hear that it makes a useful net energy contribution.
...R
Boardburner2:
websonic:
Boardburner2:
Iv been thinking for a bit on this and i would suggest you get your temp sensors and pump sorted out before you look at steering mechanisms, as without it your system will not work.That's, easy part.
Control and safety-limit thermostat with a capillary tube (3-pole) gives you nice option of 3 times NO and 3 times NC contacts.
Stooping or starting pump on desired temperature values.
Can be used even for analog input on arduino it self. (Pump not working, if high, go pane maximum left)And for pumps,now days there is wide range of water and oil pumps for reasonable price.
NO.
You need a speed controllable pump and at least two temperatute sensors.
Household type circulating pumps can be had specificaly for pwm speed control between 30 to 100%Its not a case of having fixet thermostats as the delta t has to be dynamically tracked..
Example if your water tank is at 35 deg c then the pump runs until the collector drops to 38 deg c.
When the tank gets to required temperature then a heat dump loop is required to avoid collector overheating.
An electrical divert valve is needed for that, however in your case it may be sufficient to move the dish off focus.Dont forget this system can work both directions so if the sun goes in and the pump continues it will cool rather than heat
Simple solution for this problem is adding antifreeze to water.
It keeps the water from freezing in cold temps. It also keeps that same water from boiling over.
This eliminates need for complicated plumbing and different speeds of the water pump.
This kind of approach lives you only with question when to switch on and of water pump with safety switch if medium gets to hot.
Additionally good thermal isolation of pipes and keeping them short as possible is very good idea.
Cooling is good idea, but not with satellite dish, collector is just to small for that.
Pls correct me if I am wrong.
Robin2:
websonic:
Robin 2.
That is already had done,
...SNIP....I feel I have been misunderstood again.
I am not saying I think there is a problem. All I am saying is that if it was my project I would do some measurements of energy capture before committing to the project to ensure that I wouldn't be disappointed.
I would be delighted to hear that it makes a useful net energy contribution.
...R
Winter is coming here in 2 months.
Than I will be able to do measurements my self with 1m dish I am preparing.
Robin2:
I am not saying I think there is a problem. All I am saying is that if it was my project I would do some measurements of energy capture before committing to the project to ensure that I wouldn't be disappointed....R
Quite, but how does he measure eenergy output without the pump system built.
Simple temperature measurment at the collector will tell nothing.
OP has so far failed to understand the importance of delta t.
The available energy can be simply calculated from dish area and consulting NASA published insolation values.
Some solar cos have online calcs as well.
On my 20 tube sysetem if i tweak delta t to 10 deg rather than 3 the energy harvest is halved.
Edit, ill try to explain.
If tank is at 30 degrees and collector is at 39 degrees there is energy to be harvested but gets lost as deltA t is set too high
The above figure was determined on a cloudy winter day when you want best performance.
If delta t is set too low the cost of running the pump can exceed harvested energy though.
Conversley in the summer supply exceeds demand so the pump runs using energy just to waste heat through the dump circuit so oversizing the collector for winter is not a good idea either.
With a steered collector however there is the option of steering off focus.
OP.
Antifreze is necessary to prevent freezing yes.
If the pump is still running and the collector is at the same temperature as the tank , heat will be lost through radiation.
The collector radiates equaly as efficiently as it collects.
At equilibrium if the collector recieves 1 kw from the sun it radiates 1kw at the same time. Thermodynamics.
Trick is to shift equilibrium point so it becomes a net collector.
Practically this means it should be cooled as low as possible to get best energy capture.
However the lowest temp is dictated by the store temp as it needs to be slightly hotter to transfer energy to the store.
The insolation mentioned above is only a guide, reflectors work best in direct sunlight, not so well in cloud.
So the actual amount you can practically collect depends on collector efficiency.
Boardburner2:
Quite, but how does he measure eenergy output without the pump system built.
Simple temperature measurment at the collector will tell nothing.
It was the futility of measuring temperarure that prompted my cautionary comments in the first place.
The question here is a one of those chicken vs egg conundrums.
To be honest I don't know what sort of heat tranfer system the OP has in mind. One of my concerns is that a pump would consume as much energy as the sun provides. Perhaps some thermal siphon system could be devised?
I guess the idea of your delta t is only to run the pump when the temperature difference is sufficient to justify it. As far as I can tell your system is a traditional roof-mounted series of tubes with water circulating in them. If so the water in the tubes represents a significant store of energy. But a parabolic dish is intended to generate a very high temperature in a small mass so there would not be any significant energy store and the pump would need to run all the time.
All of this supports earlier comments that the mechanism to move the dish is the simple side of the project.
...R
Thermal syphon yes.
Typically a tank is mounted above aseries of straight pipes.
Have to be straight though any bend and th syphon fails.
Normally to heavy for roof mounting
Link to a simple controller to get the op started.
http://www.reuk.co.uk/Solar-Water-Heating-Pump-Controller.htm
Using arduino would be better as it could datalog to show how well system is working.
My system uses glass tubes and water is not circulated through them.
Heat pipe conduct to hot end placed in low mass water manifold.
Outside in free air the hot end can reach 100s of deg c.
At 3 bar system pressure pump off in the sun , steam is vented.
Whatever the arrangement, delta t controller is the nor mal method of contr
ol.
Parabolic is a poor choice for this application , more suited to high temp applications such as cooking which i origionaly thought th op was attempting.
Guys,
Tell me that I am wrong,
But my impression is that you constantly have in mind solar system based vacuum tubes.
I must remind you that they are commercially sold systems.
That means lots of marketing and lots and lots of manipulated data.
Solar system based on CSP( concentrated solar power) is slowly coming on the market.
Biggest problem with CSP is complicated electronics, structure which holds everything together and mounting.
This is one example how to build it relatively cheap:
Using it just in summer for water heating can save huge amount of electricity.
I am more than willing and ready to put all my money in building CSP system.
Well, at least smaller version of it for beginning.
To motorize it
One Linear motor for TILT:
http://www.ebay.com/itm/Multi-function-Heavy-Duty-DC-12V-Electronic-Linear-Actuators-330-Pound-Max-Lift-/191299721987?pt=LH_DefaultDomain_0&var=&hash=item2c8a5a1b03
As regard to water pump, Please do not forget reciprocity ( smaller the system, smaller the pump).
Lets do not discus storage of this heat energy ( that is separate subject).
I humbly ask for your help making the code with following features:
P.S.
Links above are used just as an example.
