How to Design and Make a Low Cost, Low Tech. Solar Tracking System

Rework an antique "grandfather clock." If the whole collector assembly rotates, gear the hour hand down 2:1 to create a 24-hour clock drive. If only the reflector rotates, feeding to a static collector, gear down 4:1. The axis of rotation is parallel to earth's axis. Alternatively, there might be spring-wound equatorial telescope drives that are already set for 24-hour rotation. See http://www.instructables.com/id/Portable-Sun-Tracking-Solar-Panel-With-A-Windup-Cl/

This whole scheme assumes that the sun is shining, so you could also use a small PV panel to drive an electric motor.

could you go with solar electricity generation for your system?

With a solar powered system, tracking the sun could be as simple as a sensor with a sight guage (tube that points between the sun and sensor to insure direct alignment)

Can't rely on the wind to blow in your area every day to help wind the spring mechanism used for sun tracking purposes.

There are already electrically powered tracking systems on the market. You can also build your own control circuitry from parts ordered on the Net (Radio Shack is one source)...the plans are available online from several sources for free: Google search them Doc. The motor uses energy provided by solar PV, but has a battery backup...

The most expensive parts of the system are the geared motor and the actuators to turn the equatorial mount/solar array frame, + the pole mount and foundation.

Why try re-inventing the wheel? Just curious....

Signed CaptMoosie, LPE/PhD

I don't know if this fits your application, but I'm currently researching systems like these
http://davidmdelaney.com/scheffler-precis/scheffler-precis.html
http://solarcooking.wikia.com/wiki/Scheffler_Community_Kitchen
Seasonal adjustments are manual, but a fairly easy task.
These designs can use a mechanical (gravity driven) clockwork mechanism to track daily sun position. Resetting each morning should be a trivial task. A full 12 hour mechanism may be unnecessary. Realistically (and depending on where you live) I don't think you will gather much useful energy beyond 8 hours per day. When I find any useful designs for a simple mechanical clock drive, I will post links here.

These are some examples of gravity powered clockwork mechanisms from the solare-bruecke.org site ...

http://www.solare-bruecke.org/Bauanleitungen/clockworkmanualv3.pdf

http://www.solare-bruecke.org/Bauanleitungen/Manual_ind_07.pdf

Not quite as simple as I was expecting, but still made from common parts.

If sunshine is available, you can use a system I saw in Mother Earth News. Two pneumatic cylinders filled with refrigerant and connected to move the collector. There's a vertical panel shading one. They are connected together so that the sun heats the one on the sunny side of the panel, extending that cylinder and moving the collector. Once the sun hits the other cylinder, pressure builds there and stops the collector.

As the sun moves, it's shadow causes one cylinder to be partially shaded and the different solar heating moves the collector.

Very good idea. That is similar, if not the same as the one I remember.

it's cool to watch it reset 1st thing in the morning when the sun hits it

This is similar - the RHS frame is the container. The fluid is less exotic. Bit larger.

The original poster wanted something for solar thermal, presumably concentrating.

Which might means that the freon thing (and similar systems) are not accurate enough?

If it is 5 degrees off or more, much of the sunlight will not be concentrated on the receiver. (I know this will not matter for photovoltaic) but he said solar thermal.

Works as well in the thermal context - centers on the 'hottest' point in the sky. If it's a concentrating application, then how good is the mirror focus? how big is the receiver? what is the focus shift permissible drift? More than 5⁰ I imagine.

However; 'accuracy' is more a function of dynamic balance and receiver surface consistency/properties - or how well the thing is designed, built and set up.

Overcast will confuse it - but that usually means if there is not enough energy to center - there is not enough to usefully harvest anyway.

5 degrees is pretty much the max for parabolic dish. I do not know for parabolic trough. If they are using one of Winstons curves , the max can be a lot greater.

http://makezine.com/22/solartracker/

Nifty little solar tracking cooker made from inexpensive components.

Make Magazine is great for geeks and wannabees!

http://zomeworks.com/

Why not just use a solar (photovoltaic) panel and small motor geared down a lot. Mount the panel behind the reflector so that when it's in the shade it does nothing; when the sun shines on the panel the motor starts to run to return the panel to the shade; if there is a period of cloud cover the cooker will not move, but, when the sun re-appears the whole of the panel will be exposed and the cooker will quickly move round to the correct position. The whole cooker just needs to be reset in the morning.

Clearly the point around which the whole assembly rotates needs to be at the centre of gravity of the whole assembly including panel, supports and cooking pot.

I use WATTSON trackers systems--all the time depends on the total size your output is at each tracker--great systems and I connect a data logger to there systems and down load once a month to computer. It's called the angle of the sun dangule.

From Indonesia

I've been working on exactly this for the last year, and am now almost finished the prototype.

Details can be found here.

http://solarflower.blogspot.com/

And the main site will be http://www.solarflower.org once I get a chance to make it.

Basically it's a non electrical tracking system for a solar concentrator (or pv) which uses solar energy to boil ethanol and power a _very simple heat engine, which provides the tracking motion. Unlike clockwork systems it tracks the sun directly, rather than figuring where it should be, and unlike coolant based systems is accurate to about 1.5 degrees and not affected by wind.

There's also no need for manual resetting, and should be very low maintanence.

The project will be completely open source and the main design consideration has been that the device be almost completely makeable from scrap materials using the most basic tools and skills. Cost per unit will vary according to available materials, but I wouldn't think it would be over 100 $€£, probably closer to 30, potentially free, and each unit can gather up to 1 kilowatt raw solar. Possibly more.

I'm hoping to have the prototype up and running in the next month or two, after that I'll be making full construction tutorials to be placed on the website. Then I hope to spend the next 2-3 years travelling with the project, working with community groups and NGOs, conducting free workshops and generally getting the thing out there.

Also will be designing applications for utilising the energy, such as electrical generators, water purifiers, ovens, bio char/gas/oil/diesel, etc. These will also be as free and easy as possible.

Yes dear,

Thanx for the interest in the topic.

I will explore the links you have sent.

I must admit that your commennts defines the requirement that I had in mind, and as mentioned by you that the tracking system can be made from locally available material and general engg, skills are sufficient to run the system. Yes dear Material and skills both are important in any system which is desigened for community uses. Simple and easy to use systems have more acceptability in community uses as we shuold not expect that a well trained or highly skilled person will always be available to run the system soomthly.

Thanks a lot again.

I wish all the sucess for you system that you are working presently.

Any discussion on this or related topic is welcome.

Regards-

Dr N P singh

This is one that I have not built. You would use a soft rubber tube (like on old bicycle valves but larger diameter) that get pinched by the weight as the valve. (I know it will work because I used that old bike valve tubing successfully in a similar manner to regulate air intake in something). http://solarcooking.wikia.com/wiki/File:Gimp_equa_float_pistons.jpg It should be very accurate. It might be included in the "mecatronics" course at university of Victoria. (I was told that it would be but I do not bet on these things). So feel free to make it yourself Brian

Why use a sensor to control another power source, when you could simply fix a photovoltaic solar panel in the shade behind the solar collector. When the sun falls on the panel it drives a motor which is geared down and used to turn the whole assembly and return the panel to the shade.

Because this sun tracker circuit with a sensor will automatically track the sun, stop the tracking at sunset, and auto reset the solar array pointing back east for the next run. Basically, this is a hands off system, except for adjusting the azimuth angle for the various seasons which is a no-brainer. Works for me.

It appears to me that your mechanical geared system will require you to do the array reset manually each and every day.....labor intensive if you ask me....wanna get up at 5 AM some cold winter morings to move the array? Not me, call me lazy in that regard!!!!! LOL

Fair enough in some circumstances, but, look at the OP's requirements.

The sun doesn't come up until 8:30 am in the winter here, and disappears around 4:30 pm. If I understand you correctly, you are saying that a system that tracks the sun 360 degrees, or 24/7, is simpler? (only having to be adjusted for season/azimuth bi-weekly)

Chris

Chris, may I ask to whom you're addressing your question? :-)

If you're asking me the question, then the answer is that the electronic tracker and sensor only track the sun's radiant energy (even on a cloudy day) while the sun is above the horizon, but it cannot do it 360 degrees and 24/7.

This is for a pole mounted solar array (with polar mount, much like those used to support telescopes and clock motor drives) with actuators. After the Sun goes down for the night the tracking sensor (a diode) that is mounted on the array frame senses there's no more radiant energy, so the computer (in a sense) stops sending signals to the electrically operated actuators that are used to move the solar panel array frame. It'll stay in it's westerly-facing attitude all night until the Sun rises above the eastern horizon. When the Sun does come up, the sensor will then activate the actuators to turn the solar array panel back to the eastern-pointing day start position. From there it'll track the Sun the entire day while it's in the sky. Hope info that helps!

Randall, yes I know that the OP wanted a mechanical system, which to me is a bit archaic and a throw back to the start of the Industrial Revolution if you ask me! LOL I'm just giving him a more modern approach and another option, though either system will be adequate for use as a sun tracker........

Hi Mark,

yes, i was responding to your post. I was thinking simply of a clock drive that drives the array one revolution in 24 hours, rather like a telescope on an equatorial mount.

cheers,

Chris

hi am doing project on solar tracking system by using

1) RTC real Time Clock or LDR

2)stepper motor

3)microcontroller

4)solar panel

5)stepper motor driver circuit

I wanna just do a model. I prepared power supply circuit for microcontroller. Now i need help on how to use Ldr in this? pls send me some circuit showing connection of ldr with microcontroller

This is pretty much how my device works as well, just replacing the electronics with mechanics.

It resets itself each morning, there's no need for manual interaction at all.

Yes this is all a bit early-industrial, but then so are most of the world's population, for all intents and purposes...

(I like to think of it as steampunk :)

The solarflower is nearing completion (I mean it this time), now if I can just get German weather to calm down a bit the next and final stage is integration of the tracker into the collector.

http://solarflower.blogspot.com

I know you were asking for a solar tracking solution, but it is important for consumers to know IF a solar tracking solution is even appropriate in a solar heating collector. This is certainly unnecessary for solar room heating and usually the same for solar hot water (for bathing temperatures).

When one considers that a stationary collector and plumbing is less expensive than one on a rotating frame, and then the added cost of the frame, hinges, tracker and daily labor - it may be more cost effective to make many simple collectors instead of fewer but more complicated collectors.

Once again, for solar room heating and bathing water, if you are considering the use of heliostats to reflect light onto stationary collectors, consider painting surfaces near the collectors with white paint as a low cost alternative, especially those surfaces that may be covered with snow part of the year.

I agree, but I think he is asking for high heat concentration. "Thermal heating and cooling". Which I take to mean solar cooking and solar powered fridges. (Using solar heat instead of the propane that was used to power some old rv fridges).

I have seen some US university work on solar fridges. But they use the typical full parabolic dish and pv trackers. (I just think they are daft because the fridge has to move!)

And I guess the fridge needs to be dual powered but that is not a big deal, is it?

(If the fridge does not move).

You can still use pv trackers if you have equatorial mount. And the fridge does not move.

I am arguing against culture so I will lose.

But there is a lot of stupid culture out there. Even in technical stuff.

No you are correct,

it is daft to have a moving fridge

the return on investment is not going to be favorable & the usefulness of such a device questionable

but a university may not set out to build something that makes sense as an overall package, more of a design exercise.