Solar PV Tracker

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Introduction: Solar PV Tracker

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!

Step 1: 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)

Step 2: Making the Base, and Mounting the Wheels

To make a nice, sturdy base I cut the 2x4's at angles and put them together to make two triangles. You can make them whatever size you need, depending on the size of your panels. I then tied them together with a couple of 2x4's at the base, and a couple up top. This made a nice, sturdy base to mount the wheels to.

I cut a couple of small pieces of angle iron with a hacksaw, found the mid point on the cross members, and attached them exterior woodscrews. I put the wheels through the holes, and spun them with satisfaction.

Here is a picture of the top wheel being mounted.

Step 3: Adding the Wooden Frame to the Wheels

I then mounted the 2x6 piece to the bike wheels by drilling holes through the bike rims and the 2 x 6 and bolting them together. I also used big U-bolts to clamp the rims to the board by drilling holes through the board and clamping it down tight. The board pivoted nicely on the two bike rims.

The 2 x 6 isn't wide enough to mount the panel to, so I added some smaller 2 x 4's to the top and bottom of the board, cut to the size of the panel. Each 2 x 4 board is as long as the solar panel is wide, and was attached to each end of the 2 x 6 with screws and bolts.

This allows a nice flat place on which to mount the panel. I attached small pieces of angle iron to the holes on the end of each panel, and then screwed them to the wooden frame. This secured the panel to the frame.

Step 4: Adding the Linear Actuator

I purchased the 12 volt linear actuator on Ebay. It's built to hold up in the weather, is strong enough to move however many panels I would want to add to it, and has a long enough stroke to move the panels all the way from one side to another. (I think the stroke is 8", but I'd have to double check.)

I mounted it on the one side of the frame with a through bolt, and attached it to the movable solar panel frame. To mount it to the side of the frame holding the solar panel I just used a staple on the board that moves on the bicycle wheels. A short piece of cable goes through the hole on the linear actuator and the staple, and iIused a small cable clamp to secure it. This allows everything to move around and flex as needed when it's moving. When hooked to the battery the actuator moves the panel all the way to one side, and reversing it moves it all the way back.

The next step is giving the tracker the smarts to know when and how much to move.

Step 5: Adding the LED Tracker

I wish I had more pictures of the LED tracking unit, but there is plenty of info at Redroks website. The unit uses LED's to measure the position of the sun and tells the linear actuator how much to move and where to position the panel. It's really a slick little unit, and at a great price.

Go to http://www.redrok.com/led3xassm.htm#led3xforsale to purchase one if you want to try this yourself. There are plenty of pictures of how other folks have mounted them at http://www.redrok.com/electron.htm#led3x . I put mine in an empty peanut butter jar and mounted it to a 2 x 4. I attached the 2 x 4 to the side of the unit to get the LED tracker up above the panel to give it an unobstructed view of the sun.

Step 6: Finishing It Up

This is pretty much the finished product, and it works well. I had an issue of condensation accumulating inside the peanut butter jar and had to seal it better. The size of the tracker can be made to fit however many panels you need, and there are many ways to configure a tracker like this. I hope this was a helpful, and good luck in your tracker project!

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137 Discussions

I have just come across this project and the simplicity is what got me.

An excellent addition for my 12v aquaponics project.

Just so I can move a bit more quickly with my dimensions etc., do you recall the bicycle wheel diameter you used and the external dimensions of the solar panel you used?

At present I am thinking of 27" rims and a 57" x 26" solar panel.

Thank you for coming up with this project.

I am also toying with the idea of mounting the solar panel frame on a couple hinges with a simple adjustable protractor to better align the panel each season.

There is an easy way ati adjust your solar panel whether level or not level, any season, any sunny day, anywhere on earth, any time of day, NO MATH involved. In the center of a piece of plywood or plastic, mount a 1inch x 12 inch dowel. Place the piece on the solar panel so that the dowel is in the exact center of the array, and temporarily tape it in place. Adjust the panel until the dowel has no shadow whatsoever around it, and your solar panel is now facing head on into the sun. Remove the plywood and you will be getting the maximum output. No Calculations needed!

4 replies

This would only work if the sun did not move.

People were talking about what angle to set the tilt of the solar panel for different cities around the world. All of the suggestions were about using charts, books or internet sites to get the information. Yes, the sun moves and the tracker takes care of East to West settings; my simple solution takes care of North to South settings without the math or internet. You can reuse this dowel method to adjust the tilt of the panel manually just a few times a year as seasons change and the sun is at a different angle in the sky. It will be close to accurate and will avoid having to adjust the panel as often.

Why not modifying the frame to tilt east-west, and north-suth, implementing another sensor and actuator? Thus auto trackung would be operational to maximize effenciency year round.

As far as turning north/south, you can add more actuators
but your equipment would need to be more refined in order to run smoothly and
work at the same time. The machinery would have to be more sophisticated and
expensive to work right and you would have to spend more time tweaking to get
it to do what you want.

At my job, we installed panels in the Gulf
of Mexico. They were stationary, facing south at a 40 degree
angle. They only factored in 5 hours a day to figure power stored per day, because
the percentage is low in morning and evening.

If you really want to get completely off the grid, you have
to consider cost and maintenance.Look
at your electric bill, figure your average cost per month for a whole year. Then
work up the complete cost of your solar panel project. Divide the project cost
by your average monthly electric cost to figure how many months it will take to
start getting truly FREE electricity. If you can’t get off the grid completely
you will most likely have to talk to your electric company. I have heard that some
are starting to charge fees to people with solar panels.

OTHER THINGS TO
THINK ABOUT;

1. More parts and more maintenance will mean more costs

2. Solar panel efficiency has been increased, so you will
have to figure out which new model will work for getting the power you need,
along with the costs differences and power outputs.

3. The author, bwitmer, mentioned snow, and there are
other weather factors as well, so being able to get full solar power every day
is hard in most places.

4. At noon you get the most power, because the sun’s rays
are coming through the least (thinnest) amount of the earth’s atmosphere.

5. Haze, smoke, dust, pollen, bird droppings, shadows on
panel, and passing clouds all cut power output.

6. In winter it can be cloudy for a week or more, you
would need a back up generator, or maybe windmills in the right place.

7. Remember solar panels are DC, your home is AC. You need
a full wave inverter

8. DC loses a lot of power through long cables, keep cables
short as possible to feed the batteries

This is some basic information. There is a lot more to
figure out in order to get off the grid entirely. While I am no sort of expert,
I like to try to help out. I do my best to keep things easy to understand and
work on. Hope this helps you.

i need the preparation video.could u send me

Helios for the android can be found at the Google's "Play Store"/

It is free.

It will provide the sun's Altitude and Azimuth from anywhere on the earth 24hrs, 365days a year.

Tracking the sun works during the day, what brings the panel back to the East for the next morning sun rise? I have found that over the years a clean panel is more important than being off 20 degrees. I use the same care products as my car windshield.

windshield.

1 reply

In the last picture it shows your handy work and a rack of flat panels sitting there in a fixed position. You now have a mother/master board and you just need to make pivots for the rest of them and hook them together with a tie rod that will have all of them follow the leader. All of that with only one power unit. Great write up and idea.

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?

7 replies

I researched this some years ago and wrote a long article on the subject of fixed tilt angles. I've cut and pasted the most important conclusions and formulas below. Hope you all find it interesting and of use.

................................................................................................................................

Books and articles on solar energy often give
the advice that the tilt should be equal to your latitude, plus 15 degrees
in winter, or minus 15 degrees in summer. It turns out that you can do better
than this – about 4% better.

Fixed or Adjustable?
It is simplest to mount your solar panels at a fixed tilt and just leave them there. But because the sun is higher in the summer and lower in the winter, you can capture more energy during the whole year by adjusting the tilt of the panels according to the season. The following table shows the effect of adjusting the angle, using a system at 40° latitude as an example. (The comparison would be a little different for different latitudes.) Each option is compared with the energy received by the best possible ‘Dual Axis‘ tracker that always keeps the panel pointed directly at the sun.

Fixed Adj.2 seasons Adj. 4 seasons 2-axis tracker
% of optimum 71.1% 75.2% 75.7% 100%

In short, adjusting the tilt twice a year gives you a meaningful boost in energy. Adjusting four times a year produces only a little more, but could be important if you need to optimize production in spring and fall.

If your solar panels will have a fixed tilt angle, and you want to get the most energy over the whole year, then this section is for you. A fixed angle is convenient, but note that there are some disadvantages. As mentioned above, you’ll get less power than if you adjusted the angle. Also, if you live where there is snow, adjusting the panels to a steeper angle in winter makes it more likely that they will shed snow. A panel covered in snow produces little or no power!

For latitudes between 25° and 50°, use the latitude, times 0.76, plus 3.1 degrees.

Adjusting the tilt twice a year
Formulas used: The best tilt angle for:

Summer take the latitude, multiply by 0.93, minus 21 degrees.
Winter take the latitude, multiply by 0.875, plus 19.2 degrees.

The best dates on which to adjust and the angle from horizontal:
Adjust to summer angle of 24.57° on March 3rd
Adjust to winter angle of 62.075° on September 12th


Adjusting the tilt four times a year
Formulas used: The best tilt angle for:

Summer take the latitude, multiply by 0.92, and subtract 24.3 degrees.
Spring and Autumn, take the latitude, multiply by 0.98, and subtract 2.3 degrees.
Winter, take the latitude, multiply by 0.89, and add 24 degrees.

The best dates on which to adjust and the angle from horizontal:

Adjust to summer angle of 20.78°on April 18th
Adjust to autumn angle of 45.72°on August 24th
Adjust to winter angle of 19.61°on October 7th
Adjust to spring angle of 45.72°on March 5th

You can do all the research you want but I would bet with this back yard project arguing about 1/2 degree is silly. Bet neither one of you could get the angle within 5 degrees

RickD72, I agree that the precision isn't warranted for this particular project, but I was actually replying to anjnugteren's question which specifically asked

"Is there and equation to calculate the inclination i need to set the panel to for any given place on the world?"

On my own tracker I have no problem setting it to 0.5 degs, using a digital inclinometer.

What is so difficult about adjusting a sturdy frame within 5 degree?

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.

filmnuts i agree with you as i laughed about your post! I used to attempt this in september on a saturday with the guys over for the football game on t.v. a lot of Einsteins after 4 brews and "i just didn't know what i was doing" say them all without any panels of their own.

That's DEClination and you need to set the normal to the axis to the COlatitude (90-latitude).