Tracker on a timer

[Cor van Houtum]

Does someone of you solarfriends have expierience with a solar tracking
based on a timer that turns 15 degrees every hour.

the longest day here is 16 hours of sunlight
so 8 hours before and 8 hours after the highnoon.

when i put a clock on every hour starting and stopping all the year the same
knowing that in winter the first hours and the last hours are not usefull to let it turn
but on the otherhand it does not harm either.

do you think this works

[Dave Schwartz]

It will work better than a fixed array because the sun will be closer to perpendicular to the array much more of the time. The apparent motion of the sun due to various factors of the Earth's orbit and rotation does not quite match the 15 degrees per hour that 360/24 would seem to imply but it will get you in the ballpark.

If you really want to know the sun's azimuth position, this is a great resource (http://www.sunearthtools.com/dp/tools/pos_sun.php). Just enter your location (51.62361 , 5.55915) in the coordinates and pick a few days throughout the year.

[Cor van Houtum]

I want to make a tracker without the use of intelligent electronics

i use 2x a timerclock (normal plug type)
and one micro switch double working

the microwitch will be mounted on the outsite of the standing part of the pole
so the switch is standing stil

on the turning part of the pole there is a flange that turns
on the outsite of the flange i will make higherparts (increase the hight) and lower parts.
the distance and the lenght of these parts make the resolution of the movement

lets say i have a higher part with a lenght of 10cm
and then a lowerpart with a lenght of 10 cm
again a higherpart and so on

the microswitch follows the higher and lower parts
the center of the switch is connected to the motor
the first switch connection is connected to timer 1
the second switch connection is connected to timer 2

(OFCOURSE THERE IS A AC/DC POWER SUPPLY IN BETWEEN)
You can use this from a old printer or someting that matches your grid and motor.

HOW it works

Asume we are in the home position facing east.
the switch is in the lower position
the timer of the lower position goes on for 15 minutes
the motor starts turning and will stop after 10 centimeters
this is when the microswitch hits the higher first reef.

basicly it kills it self

that the timer is working for the next 15 minutes is no problem
it wil stop automatic after the preset time

then after 30 minutes the second timer will go on
becouse the switch is on the high part (reef) the motor will start to turn
it will fall off when is goes past the higher part and stops again

then the first timer will come in again

and so on and so on


in the programming of the timers i can play with the day time
the resolution and the steps are depending on the number of high and low parts on the
ring that moves

Because i use a liniar motor drive to turn the panels
this liniar motor has his own stop when it is on the end
to prevent it from burning.

Now i use a third clock independent from the others
this one is set at 23:00 hours for 15 minutes
this one is connected to the motor in reversed polarisation (second trafo)

When this timer comes on then the motor will turn maximum to the other site
and that is the beginning of the next morning


It seems a lot of work to make it,
but I was reading some of the comments on this blog and think that there are a lot of people out here who can go easy with relais and wires and switches but when it comes to electronics it is hars to make and understand.

on the other hand my system cost allmost nothing
and is easy to follow.

please comment
I like that

[Dave Schwartz]

Ahh, yes, the single-axis tracker (http://en.wikipedia.org/wiki/Solar_tracker#Single_Axis_Trackers).

There is a reason these are commercially available - there's a fair bit of engineering involved in creating a good one due to the worst-case forces and loads involved. Building one yourself, you will want to over engineer it because the cost of failure will be quite high (your array sails away and crashes into your neighbor's house). Just figuring out where to point it when is the easy part - making it do that reliably, day-in and day-out in all conceivable outdoor conditions is the hard part.

[Steven Fahey]

It often happens that a solution for a task in one industry is sought, but it has already been solved in another realm. I have seen some very clever ideas for detecting differences in the relative position of the sun and tracked array but this is really over-thinking the problem! The earth turns at a constant rate and so should the solar array. The only "decision making" ability necessary is for the panels to return from west to east at the end of the day. This can be very simple.

Mounts capable of turning telescopes weighing hundreds of pounds are avialable. Since the attachment of a tube is not appropriate for your need to mount a flat panel, you can dispose of the big forks. Tracking errors of an arc-second are intolerable in astro-photography, but for your purposes, errors of several degrees are perfectly acceptable. You do not need every 1/1000 of the precision of a telescope mount.

This says to me that building an equatorial mount for a set of solar panels shouldn't be hard for an adept do-it-yourselfer. Very large step-down ratio gears are the only thing that you might prefer to buy instead of make.

[Joe Blake]

Back in my early teens I purchased a book on making a reflecting telescope (which book convinced me to buy a ready-made 'scope) and one of the chapters was making a tracking drive using the "hour glass" principle. As the sand ran out of one bucket into another, it made the bucket lighter, and another (full) bucket of sand provided a counterweight, which moved the telescope. When the top bucket was empty, it was replaced by the full bucket ad infinitum. Pity I can't remember more on how it worked.:huh: I just remember that the speed of tracking was governed by the size of the hole in the bucket. The bigger the hole the faster the 'scope moved.

Perhaps looking around on the 'net might provide an answer.:embarrassedt:

Joe

[Dave Schwartz]

Steven's description is actually covered in that Wikipedia article - its called the Tilted Single Axis Tracker (specifically, the Polar Aligned Single Axis Tracker when you align the tilted axis to the pole of the earth's rotation).

However, even if you simply considered the weight, its orders of magnitude more than what consumer-grade mounts could handle (yes, you could trade off accuracy of tracking for robustness by using really big components). Also, telescopes are only used in quite calm conditions or inside a dome where the wind loading is virtually zero and can be ignored. However, that is completely impossible to do for a solar array that has to stand out in the open 24x365 so you have to account for worst case wind load at your location. Your building department will probably want to see engineering approvals accounting for 120 to 150 kph wind.

Of course, the building department will only care that the array or no part of it will depart from its attachment to the earth under the worst foreseeable case. They won't care that the wind loads will break the drive mechanism and it will flail about uselessly damaging itself... but you will because you'll be out there spending money and time to fix it all the time.

[Joe Blake]

Obviously everything will depend on how big the array is, but it's possible to build a geodesic dome out of PVC pipe to cover the array and mounting.

http://i82.photobucket.com/albums/j245/saxeharp/general/dome05.jpg
http://i82.photobucket.com/albums/j245/saxeharp/dome04.jpg

and it can be covered with heavy duty transparent plastic (as in the picture except not black of course :D )

http://www.desertdomes.com/formula.html

The size of the dome is governed entirely by the length of the struts. There are two different strut lengths, which are governed by a formula which is a proportion to the radius of the dome. For a dome which is 1.75 metres in radius the A strut is 1.08 metres, the B strut is 0.96 metres.

The black plastic in the photograph lasted some 3 years without any attention, other than need to have some of the cords replaced. The dome was anchored to the ground via some tent pegs and synthetic cord. The frame stayed fixed in place for over 10 years.

I've since designed a new method of assembly which is simpler and can be pre-assembled to a larger degree for transportation to a remote site.

http://i82.photobucket.com/albums/j245/saxeharp/general2/P4150002.jpg


Joe

http://i82.photobucket.com/albums/j245/saxeharp/general2/u15208845.jpg

[Dave Sloan]

I am just finishing up a tracking system and agree that at a certain degree of tilt it is not worth tracking any more because the wind factor outweighs the tracking/production factor especially in northern climates. The payoff of tracking in the summer months (double) is worth building a tracker providing the expenses do not get too high to take care of the wind factor. This time of year at the angles that a panel must be tilted - it is better to add some guy wires and structure to the system and let the MPPT take over. As far as electronics and timers - the simplest I have seen is the Redrock which does not rely on pre-calculation and complicated electronics AND is very inexpensive = 40 dollars. I am still relatively new to this but have studied the alternatives for about two years before picking the options. There appears to be lots of real time experience on the internet and because of this I feel that it is better to improve on other peoples experience = it is much less expensive.

[Cor van Houtum]

Hello Dave,
I am also busy with my tracker system
hereby some pictures

[Cor van Houtum]

picture from the back site
I need to put a bigger motor on the system
but the yaw point is from a 5kw windgenerator so this one is very strong

[Joe Blake]

Thinking outside the box a little; rather than moving the PV array, have you considered a light reflector on a track which will move with the sun reflecting extra lumens onto the array?

I'm just building a larger reflector (flat) made out of old CDs cut into hexagons, and mounted on a frame of PVC pipe. It's still in its early stages, but I think it should be fairly inexpensive, lightweight, semi-permeable to weather and recycles something which there is no shortage of!

My initial prototype gave a measured increase of up to 10% power generated in very sub-optimal conditions.

http://i82.photobucket.com/albums/j245/saxeharp/general/Picture21.jpg

I used a paper guillotine to cut them to (roughly) the right shape.

http://i82.photobucket.com/albums/j245/saxeharp/general/Picture32.jpg


Joe

Apologies for the quality of the photos, but I had to use my webcam. J

[Dave Sloan]

Hello Dave,
I am also busy with my tracker system
hereby some pictures
Nice solid system - looks like you need a good actuator. I picked up a couple on Ebay for less than fifty dollars - 36 inch extension. Luckily I had my panels mounted in the winter position before the low we had a couple of weeks back. Those 80 mile an hour winds would have really pushed the limit on a tracking mount position. As you can see in the picture the position allows for tracking and fixed. The bottom slides in once the steel pole is lifted above and the poles at the other end are lowered for summer rotating position. Hope to get everything wired up this week now that I know that it is going to stay put. The platform was made to the same strength as my roof. Just did not want to see my roof take off since I just got new 50 year shingles.

[Cor van Houtum]

At this time i am busy to build a tracker with two axis
the position is coming from a plc that calculates the solar elevation and azimuth

so far it works (without pannels) we install them later

[Ulf Hansén]

Hi Friends
I Have now mounted solar panels and solar cells

log in to http://www.solarthermalweb.com
username : skanevind
password : smirben
and you can see the solarwaterheating:)

I have no web display on the wind generator or cells but I thing it will be solved later this summer. How much is a solar tracker system do on a yearly base in Europa in percent ?
It looks like a fun project to solve,it is more fun with self made things ! ( we have to talk more about this Cor)

Ulf

[Cor van Houtum]

hello Ulf,
this is realy fun stuff to work on
I have build the tracker completely my self with use of professional motors
expect this week the pannels to mount
18 pcs of 180 watt will be turning
I connect this with a aurora inverter
also a wind meter will be mounted and the tracker bed will go horizontal when the windspeed exceeds limits,
also planning to put snow sensors on the system
then it will go in vertical position to lose the snow



I keep you informed

Cor

[Cor van Houtum]

Hello solar friends,
After months of hard work the prototype of our draaistroom solartracker is finaly working as i tought it would do,
To give the unit a hightech look i have used stage truss systems. To make the solar panel bed.
This is 6x6 meters outside
The unit is double axis and totaly made and welded by our selfs
We used motors from a german company called Hanning what seems to be the right choice.
The system is programmed to follow the sun on GPS data
We have mounted 18 panels x 180 watts and connected them to a aurora 3.6 kw
In two strings of 9

We want to put this product in Holland on the market.
A smaller version with 8 panels is the next project we want to create

Look at my pictures, and feel free to give your opinion

Kind regards
Cor

[Rob Beckers]

Good looking tracker Cor!
I know you were originally planning some form of automatic (but passive) tracking simply based on a timer, but it always seemed much easier to me to use calculated sun position. Processors are cheap these days. The most-used tracker over here is a German brand, Deger, they make massive 10kW dual-axis structures. They also still use a very simple 4-quadrant photocell electronics device to aim at the 'lightest' point in the sky. That works so-so, if you have multiple trackers in a field you'll see them all pointing slightly differently, sometimes massively differently. Why they haven't changed to calculated position is beyond me (of course, their marketing department puts a spin on it claiming more energy can be produced because in case of clouds the brightest spot in the sky is not the sun, but that's hog-wash).

What do you do to protect in case of high winds and snow? Is there a wing sensor to take the array to 'tabletop' position? Or is this designed to handle the full wind speed in any position?

-RoB-

[Cor van Houtum]

Hello Rob,
thanks for the compliments

The tracker is based on GPS data 365 days in a resolution of 15 minutes
there is a wind anemometer that gives the input to the plc to table top the bed in high winds.
i have made a remote controll with camera and controll on the internet router
in this video you can see me controll the unit from home
the tracker is lokated at my company in Veghel (Netherlands)

we want to build a smaller version in a short while

kind regards
Cor

video
‪draaistroom solar tracker‬‏ - YouTube

http://www.youtube.com/watch?v=RC5EMfAIJsk&feature=player_detailpage