Instructables
For a class project (PV Design, Appalachian State, Dr. Dennis Scanlin) I decided to try making a low cost PV (photovoltaic) tracker. Being able to follow the sun's path through the sky can raise your solar panel system's output considerably (30-50%), but the argon filled ones can be a bit pricey, and seem to be a bit unsteady in wind. I looked at several different designs, looked at what materials I could find, and this is how I did it.

The panel is mounted to a frame, which is attached to two bike wheels. The wheels are mounted to a larger wooden frame, and the wheels and panel are moved by a 12 volt linear actuator. The sensor is an LED model and is purchased from Redrok Energy.

The LED sensor senses the path of the sun and tells the actuator how much to move to keep the panel properly oriented. At the front of the tracker are two legs that can be adjusted to the proper altitude for seasonal changes.

I used bicycle wheels because they are durable, strong enough to handle some weight, and best of all, in my case, free!
 
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Step 1: What do you need?

Picture of What do you need?
Here is what I used to make this tracker, and where obtained:

*Several treated 2x4's (Lowes)
*Two wheels from a free bicycle- free or almost free bikes are pretty easy to find from the local landfill or thrift store
*A piece angle iron with pre-punched holes (Lowes)
*A 12 volt linear actuator-(~$75?)- (Ebay)
*An LED tracking sensor- (~$40)( http://www.redrok.com/led3xassm.htm#led3xforsale )
*Various nuts, bolts, screws, cable and wire -(scrounging around my workshop)
pkalinowski15 months ago

I was looking into solar trackers when I found your project. Very nicely done ! I would also like to point to something I have found on youtube => https://www.youtube.com/watch?v=ljTJqQYSJ8g

rmasre12 months ago
briliant
rmasre12 months ago
u r brilaint
I love the idea of solar or wind energy but dont know too much about them. How much power does this give and how can it be used inside?
metwally1 year ago
cool and nice many thanks for the helping people.
metwally1 year ago
cool and nice many thanks for the helping people.
Wunderbar122 years ago
Hi Team,
Here is Wunderbar 12,
Just an update on my Bike tracker Project.
After building 2 and got them working by hand, I was a happy person, sending a photo to my friend a German Tool Maker, he warned NOT to build my trackers like this, as the roof is not a good environment, and he believes I must redesign the lot to do without the Bike wheels. He said you have 30 years warranty on this solar panels, and the wheels will fall apart after 3 years, when I am also 3 years older!
We started on the redesign, so far so good, when I have a array going, I am happy to post a few photos.
Yes it is NOT easy to build something low priced but high Chocolaty,
Have a good KW day! (KW stands for Kilo Watt)
Wunderbar122 years ago
Hi bwiter,
Thank you very much for your WUNDEREBAR Idea. I love it so much!
I have just copied your tracker, I used my existing Alu frame. I am waiting for some panels to complete my test unit. Then I will give you some Photos.
I will build 108 trackers, as I have 9 arrays of 12 panels on my very large roof all up 30KW. My production is down to 100KW average per day. I need to get 150+KW to repay my $80,000 loan.
I adjust the angel every month, but I find I need to track East - West the panels for more production.
We got winter here in Brisbane and it is nice to work on the roof now. Can anyone help me: I will put the panels 250mm apart and join the trackers with a rod to have 12 trackers working of one linear actuator, with this nice freely movement of the bike wheel, I am sure I will get it working, the shade problem is my worry, right now in winter I find 250mm a bit to small, but I need to save some room, would 500mm be better?
Any comment would be welcome.
Thank you again, you Gays are helping me a lot with all your input.
E-mail: Solar_Lover@bigpond.com
hdb1113 years ago
Should two Linear Actuators be used for a larger array? Say Four Panels?
Thanks folks.
redrok hdb1112 years ago
Hi hdb111;

I think I understand what your asking:
Can one drive multiple independent linear actuators from a single tracker.

The simple answer is no. Due to friction and different weight balance they tend to get out of sync.

A better, and cheaper, method is to link multiple bicycle rims together with a cable. A single actuator moving the cable can drive quite a few panels.

Note! These multiple panels should be separated so there is minimal shadowing.
I have a Excel spreadsheet that deals with shadowing issues. See:
http://www.redrok.com/led3xassm.htm#shadowing
http://redrok.com/Shadowing1.xls

Duane
Red Rock Energy
redrok.com/led3xassm.htm
ensoarts4 years ago
ALL electronics has a linear actuator for 36$ but its also 36volts,  Do you think you could string 3 panels together to power the actuator. Will the redrock run on 36vs?
redrok ensoarts3 years ago
These types of actuators use permanent magnetic DC motors. Just run the 36V, or 24V, actuator on 12V. They will move slower, a good thing, with little loss in force.

Duane
Red Rock Energy
redrok.com/led3xassm.htm
wmiles redrok3 years ago
Will the 12v be enough to trip the relays though?
redrok wmiles2 years ago
Hi wmiles:
There are no relays in linear actuators.
Just the motor and asociated limit switches.
Duane
Red Rock Energy
redrok.com/led3xassm.htm
Steevvee2 years ago
On the redrok site, the pictures show the LED tracking sensors attached to the moving reflectors. Your picture shows the sensor attached to the fixed frame. Does your arrangement track OK?
Great project but honestly it could be so much more better looking. Please may I suggest that you find a hippy, artist friend to carve some awesome nature scenes into the wood, faries, suns, moons, stars. etc, then stain it, and you're ready for the solar festivals.
Xzav3 years ago
I'm new to the electronic field and sometimes it seems intimidating to me. About the Led tracker, do I need to know how it works in order to use it? I would like to know how it works. Can you explain a little on it. Thanks
Shiftlock3 years ago
"Bicycle wheels, working tirelessly (no pun intended)"

No pun intended? Really? Because it sure looks to me like you absolutely intended to make that pun.
Xzav Shiftlock3 years ago
It was still funny.
I want to add this tracker to my solar array over the next month or two. It seems the largest consideration is going to be which linear actuator to use.

Obviously if you can find a free or cheap one from someone who is junking an old satellite dish that would be great.

But if left to buy one, other than the stroke and finding one of the appropriate voltage, how much force should one be able to exert on say, 2 45W panels and still be able to operate in blowing winds? It seems like you would want to minimize this in order to draw the lowest amount of current from your battery bank so that you gain the maximum power from your tracker and invest as little power as possible into driving the thing. Thoughts?
Gunkarik3 years ago
Very helpful, thanks for sharing!
kd4uwk3 years ago
Thanks for sharing the photos are good
segarza3 years ago
A nice simple and effective design. Thank you for sharing it. Isn't it funny how the minute you share your project with the public, we instantly began re-analyzing and re-designing it to death and flooding you with a million ways you could have done it better? Oh well, that's just human nature I guess. You did a great job!
You know you could have said that a better way LOL 9-)
Yeah, I know...I had that one coming didn't I? lol
tbone563 years ago
Thanks for making this. It is truly instructable.
I have a question about the movement.
How many degrees do the panels move each day?
kosme3 years ago
great project
jakesnake3 years ago
red rock just keeps your money
Great work.. Now I just got to get a solar panel to put on it hehe Thxz for the post.
jolshefsky3 years ago
I really like the design where you bolted boards to bicycle wheels -- it's an elegant, strong solution that uses (as you mention) free resources. Even bent rims would work fine.

I'll have to give this some thought ... I'm working on a design for an "external Trombe wall" which I can attach to an existing window for the venting.  Of course, making it insulated, situated off an existing wall, and now pivoting, I'm getting away from the simplicity of Trombe's design.
ktkeith4 years ago
Not to denigrate the work you did, but do you really need the photo sensor? The position of the sun can be calculated for any time of day, any day of the year. Why not just program an EPROM to store a lookup table for the correct angle, hour by hour, day by day (about 4,000 data values for the daylight hours of a single year), and use it with a simple microcontroller to adjust the angle incrementally? A bit more complicated at setup, but probably about the same total price, more accurate, and likely more reliable.
Uh... How about because his approach is considerably easier and cheaper? And didn't you read about the brightest part in the sky not necessarily being where the sun is?
bwitmer (author)  ktkeith4 years ago
Sure, there are many ways to do it without using any sensors, this is just how I chose to take a crack at it. The reason I went with the sensor over the EPROM is that I know how to hook up the sensor, but have no idea what an EPROM is.
Is there and equation to calculate the inclination i need to set the panel to for any given place on the world? Or is a matter of guessing towards optimization?
If your panel has a fixed inclination (as the one in this Instructable does), you usually want the angle to be the same as the latitude of the panel's location.  A location's latitude is very close to the mean sun height over a year.
Laral filmnuts4 years ago
That's DEClination and you need to set the normal to the axis to the COlatitude (90-latitude).
redrok Laral3 years ago
Some also call this Zenith Angle
Laral redrok3 years ago
There seems to be enough confusion without adding yet another layman's term. Why not just stick with standard astronimical terms?

http://en.wikipedia.org/wiki/Declination
filmnuts Laral4 years ago
You're arguing over semantics.  Inclination and declination are complimentary, as are latitude and colatitude (the equation you give for colatitude is the equation of a complimentary angle).  To say the inclination and the latitude are equal is the same as saying the declination and colatitude are equal; the former is just easier for most people to understand because they already know what latitude means and how it relates to their geographic location. 

Also, the original question asked about the inclination of the PV panel, not mean annual solar declination, so I gave my answer in terms of inclination.  Declination is primarily a astronomical term, and though using it here would give you the same results, it's not technically the correct nomenclature, as we are not directly discussing the sun.
Laral filmnuts4 years ago
The word is complEmentary and I'm not arguing about anything. You seem to be doing that for both of us. ;-) And yes, declination IS an astronomical term and it is highly relevant to the discussion since ignoring the solar declination will definitely reduce the overall energy efficiency. If we're not "directly discussing the sun", then what are we discussing? And no, the declination is not the same thing as the "inclination", as you put it, or the latitude, at all. Declination is the angle that the sun makes relative to the earth's equatorial plane and it varies between +/- 23.5 degrees. At either extreme, only about 90% of the light energy is reaching the cells if you don't compensate. The astronomical term "inclination" refers to something entirely different from the latitude:

http://en.wikipedia.org/wiki/Inclination

If by "inclination" you mean the angle that the axis of rotation of the mount makes with the horizontal plane then OK. You need to align the axis in your local meridional plane, that's the plane that cuts through a north-south line at your location, and tilt the axis toward the sun so it is at an angle equal to your latitude. Then you need to add the declination angle throughout the year for maximum efficiency. You can easily calculate the angles or find a table and make a simple scale that allows you to quickly change the angle for any given week.

To put it simply, for your sake, make the angle of the frame equal to your latitude and align the axis in a north-south direction.

Before replying, do some homework this time.;-)
Again, that's DEClination, and here's a simple equation to calculate it:

http://pvcdrom.pveducation.org/SUNLIGHT/DECLIN.HTM

You then need to add the result, which can be positive or negative, to your COlatitude to get the current angle that the normal to the rotational axis should be at.
filmnuts Laral4 years ago
I would not call that equation simple (yikes!), but it is helpful for finding the solar declination on a given day and would definitely come in handy with a PV panel that pivoted on two axes.  However, as I said below, this equation is not necessary, as long as you are dealing with a PV panel with fixed inclination.  The optimal angle will always be the same as the latitude of the PV panel.  It's a fact.
Laral filmnuts4 years ago
Well what's NOT simple about a multiplication, a subtraction, a division, and a sine? If that's not simple to you why did you even ask if there is an equation if you are not prepared to use it?
This is a well thought out project! I may have missed it ;but, how does the device return to the morning position after it follows the sun until sunset?Again many thanks for sharing your work!
Parking is built into the LED3X.

When it gets dark or with heavy storm clouds it heads toward the Eastern limit switch. If the sun comes back out it resumes tracking.

Duane
Red Rock Energy
redrok.com/led3xassm.htm
shetonus4 years ago
I like the concept of pointing your solar panels at the sun, and have suggestions for improvement:

1. I would suggest that the wheels be mounted on an A-frame so that struts could be placed from the outside edges of the panels to points tangent to the wheel to provide bracing against strong winds. 

2. I find that sun position sensors aren't really necessary for pointing since we already know where the sun will be at any given time of the day.  Also, some sun trackers may have difficulties tracking the sun's position on overcast days and may operate erratically on partially sunny days when clouds intermittently block and reveal the sun.  A system built around small uProcessor with an on-board clock can be programmed to provide positioning information to your drives, and if you want to get fancy, the sky's the limit for adding sensors, providing web connections, what have you. 
redrok shetonus3 years ago
For PV panels and the like the sensor method is superior to the clockwork methods because they find the brightest part of the sky. Yes this may not be where the Sun is behind the clouds.

If you measure the power from the panel this other direction will be greater.

Furthermore, the sensor is influenced by other sources of light such as reflective sand and snow adding even more power.

Duane
Red Rock Energy
redrok.com/led3xassm.htm
Just a thought about item #1... Cables could be used instead of struts if the PV panel were sufficiently sturdy. 
spicegal274 years ago
can you please help me in buildind a similar model for ma project....plz suggest me some books
Laral4 years ago
Looking at the finished design, I see an easy mod you can make to compensate for the sun's declination. You can mount the panel on hinges at the top with metal straps with holes at the bottom like you did for the front of the mount. You need to add enough wood at the top to allow a -23.5 degrees tilt at the bottom and a long enough metal strap to allow a +/- 23.5 degree tilt. You can add a simple scale with markings for each week or 2-week period of the year for manual adjustment, or you could theoretically add another actuator. BTW why didn't you just cut the angle of the 2x6s the same as your latitude. You're not going to be moving this around are you?
Good suggestion. I have something very similar on the tracking solar accumulator videos.  At this time of year and in the winter there is only a tiny adjustment in 2 weeks. Around equinox there is a large adjustment. You might adjust every week  to get maximum performance. The image has the seasonal adjustment shown as you suggest. Hopefully it is clear enough at this size.
Brian
equamount-page1.png
speedstix4 years ago
Cool! For a class project our group and I decided to make a Maximum Power Point Tracker. It did not track the sun but it did try to find a point where the panels were operating at their maximum power. I am wondering what sort of efficiencies have you achieved using this setup. Did you do any tests between stationary vs tracking power measurements? I am very curious.
Speedtix, FYI NREL has a huge data base with measured solar radiation data that compares fixed vs. 1-axis and 2-axis trackers. It even even includes the impact of tilt (declination) and there is data for every month of the year. Very useful resource for anyone out there trying evaluate the potential benefit of various schemes for their particular location.
Go to: http://rredc.nrel.gov/solar/pubs/redbook/
I suggest going down to the middle of the page where they have individual state data. Note that for EVERY location they provide annual data for ALL the relevant mounting and tracking schemes. Your tax dollars actually at work!
Hope this satisfies your curiosity on this topic!

bwitmer: great instructable!!
skwerp4 years ago
HELL YEAH APP STATE
I think you did a very good job.
I have been working on a model for equatorial mount. Mine is for solar concentrators but it is much easier with pv panels.  The model is for the norther hemisphere up as far as Calgary.
Rotate the frame  at 15 degrees per hour to keep it pointed at the sun.
The actuator can do that. The panels can have adjustment manually for sun elevation with this mount.
IMG_1101.JPGIMG_1096.JPG
bwitmer (author)  gaiatechnician4 years ago
Very cool, and thanks. I enjoy reading your Instructables, by the way!
Laral4 years ago
I like the overall design of this but one big improvement that would take very little extra effort would be an equatorial mount. You need to align the bicycle wheel axis to the earth's polar axis and keep it there as the sun's declination varies throughout the year. You already have your right ascension (RA) axis so all you need do is add a declination axis. You need an axle at a right angle to your RA axis mounted on two triangles of plywood. It would be very simple to do.
bwitmer (author)  Laral4 years ago
That is a great improvement, thanks for the idea.
bplaisted4 years ago
Sensors Schmensors!
All you need is a timer.  If the sun ain't where it's supposed to be at any given time of the day then perhaps we're on a different planet.  With a single axis tracker its easy. 
bwitmer (author)  bplaisted4 years ago
Sounds like a good idea! Looking forward to seeing your Instructable on how to do that.
Linear actuators are one way. Have a lookie at ATM, website for amateur telescope making. They have tried everything under the sun (pun intended!) and there are articles on helioscopes for solar tracking. nice job! enjoy it.
I would think you could use the one tracker to control multiple actuators. you would probably need to set up a relay to accommodate the increased power load when the actuators are on.
 
A mechanical linkage between PV modules with one larger motor driving all would be less expensive than a motor on each module. 
If you are having difficulties with the condensation in the peanut butter jar,  you could always use a descant. like the little packets that come in shoes, and with dried foods. they usually have little clear balls and are in a paper packet.
 
chrwei4 years ago
how strong is the actuator?  Could you build several of these stands and link the tilting parts with static arms and have one actuator and tracker move all of them in unison?
alex young4 years ago
Hi how are you . Your project look great. DO you have the wiring diagram for the sensor. Thank you
A year to the day !! Hope I can get this answered !! RE: 12v linear actuator; HOW LONG SHOULD THE RAM BE ????
jdagol5 years ago
do you have pictures or diagram on how you wired the actuators with the redrok sensor/tracker?
gamefreek5 years ago
how can i make my own Solar pv on my ipod touch? can you help.
what?
tspnews5 years ago
You could put some "do not eat me" moisture absorbers in the jar, might help with the moisture. I always have them from certain vitamins and jerky :-) -T
A handful of rice could also work.
rice is also know to be absorbed by birds
LazarusMan5 years ago
I wonder if a single actuator would be strong enough to move multiple panels. It would be fairly simple to add a linkage between several mounts. That would help with the cost for a system of tracking panels.
I don't have any experience with this actuator so I can't say for certain, but if you could counterweight the bicycle wheels so that they are balanced it would take all of the strain off of the actuator. Just a thought!
Great work!

My blog features "off-grid" solutions, and affordable alternatives to housing and power!

Would you consent to my featuring your Solar Tracker on my blog?

My readers would really appreciate this!

Ronin
bwitmer (author)  solarpaneltalk5 years ago
Sure, be my guest! Thanks for asking.
chrisnotap5 years ago
Man what a sweet unit! Nice job. The wheels are the perfect rotation device and the actuator would have no problem moving the panels. Very nice. I was wondering if these trackers can be used or set up to control a mirror to continuously reflect the sun at a fixed item?
tubajoey15 years ago
hahaha!!! I applied to App! Hopefully I will be up there this coming fall! Great project!
Plasmana5 years ago
Wow! That is really cool!
ldonuke5 years ago
Cool idea. Looks like the actuator would be a significant weak link in the system though. We get Santa Anna winds here that rip my fence down at least once a year. I see the potential for the actuator to get ripped off and the nice low friction wheels slamming the PV panel back and forth to destruction. Maybe a potential upgrade would be to have a wind sensor and send the actuator to a "home" position where the array can get locked down in high wind conditions. Keep up the good work!
bwitmer (author)  ldonuke5 years ago
Good suggestion, and thanks. Being able to handle wind was definitely a consideration, as it gets really windy up here in the Western NC mountains. Like you said, having the panel slamming around is a bad thing. I anchored it into the frame with the biggest bolt that would fit in the actuator, and used the biggest diameter of coated cable that would go through the other end. I don't think the wind would pull the actuator apart, and everything else seems pretty strong- at least so far so good. Also, at night when it gets the windiest here the panel is parked to the west, which seems to form a windbreak for everything.
filmo5 years ago
Can you use 1 tracker to control several different actuators?
bwitmer (author)  filmo5 years ago
That's a good question- I would think so, but I haven't tried it. Duane over at Redrok is very helpful, and could give you the right answer on that.
tburkhalter5 years ago
OK, come on down to Asheville so we can build a couple of those. Very cool stuff Brian. Todd
i am very pleased
PS1185 years ago
Linear actuators are too expensive to believe. Maybe a person could use a motor running along the radius of the wheel... ...Although, if you're vititing a junkyard anyway, a power car antenna might work for a linear actuator.
bwitmer (author)  PS1185 years ago
I paid about $70 for mine on Ebay, maybe I happened to get a good deal but a quick search showed that you can easily get one like mine for $100 or so right now. Even if you have a couple of hundred bucks in this kind of tracker that's still much less than a commercial model.
I've also seen adds for these dishes offered for free if you remove. Doing so can also provide some valuable hardware.
bwitmer (author)  niteshft5 years ago
That's a great idea!
niteshft PS1185 years ago
Linear actuators used on older satalite dishes are commonplace and rather cheap thanks to the newer providers and thier small stationary dish.
action_owl5 years ago
about how much electricity is output with a panel that size?
Maybe I missed it, but he didn't mention it so I am going to guess at about 50-60w production from that panel.
bwitmer (author)  braddd5 years ago
I'd have to check the panel, but I think that's right and that it was about 60 watts.
niteshft5 years ago
Actuators can be gotten cheeper (if not free) thanks to the like of Direct TV. Alot of older satalite users are switching to the newer providers. These older dishes used actuators to position the dish to various satalites.
yeah Bernie!
dwitmer325 years ago
Wow, just absolutely fantastic!
johnedscalf5 years ago
nice!
nolte9195 years ago
You ought to explain what PV stands for, perhaps even in your very first sentence. I'm guessing "photovoltaic" but that wasn't obvious to me at all. Maybe make the word photovoltaics a link to Wikipedia. Just a suggestion. Great Instructable.
Bwit, Nice Project, do you have any comments to simplify the circuitry that is less complicated than Redrok's explanation? Thanks, DBagmanofsky
robotkid2495 years ago
To bad it not dual axis that would be cool
cool, thanks
jeffasu5 years ago
A tip of the cap from an ASU alum to a fellow Mountaineer.
foobear5 years ago
very cool
rimar20005 years ago
Very good work, congratulations.