DIY Solar Tracker using Arduino

DIY Solar Tracker


We aim to introduce young students to engineering and teach them about solar energy; by having them build a Helios as part of their curriculum. There is an effort in engineering to push energy generation away from the use of fossil fuels and towards greener alternatives. One option for greener energy is to use a device called a heliostat, which uses a mirror to direct the sun’s light onto a target throughout the day. Such a device can be used for many applications, from concentrating solar energy onto the heat reservoir of a power plant to illuminating areas that are blocked from the sun.

In addition to the number of uses of this technology, there is also a diverse range of structures that have been designed to enable solar tracking. The physical structure of Helios’s design, as with other heliostat designs, functions to mount a mirror onto two controllable axes. The mechanism will track the sun by using a program to calculate the star’s location in the sky thought the day, based on the global position of the Helios. An Arduino micro-controller will be used to run the program and control the two servo motors.

Design Considerations

To ensure that this project is widely dispersed, considerable effort went into designing the Helios to be built with common tools and cheap materials. The first design choice was to build the body almost entirely out of foam core, which is rigid, affordable, easy to acquire, and easy to cut. Also, for maximum strength and rigidity, care was taken to design the body so that all of the foam parts are either in tension or compression. This was done to take advantage of foam core’s strength in tension and compression, and because the adhesive that was used is more effective at supporting a load in tension than in bending. Additionally, the shaft that is attached to the mirror is powered through a timing belt, which allows for a small alignment error between the motor and the mirror, the servo motors are accurate to within 1 degree, and the platform runs on the open source Arduino platform. These design choices, along with a few other considerations, make the presented design a durable and affordable, educational tool.

DIY Solar Tracker

Our open-source promise

The goal of Helios is to promote engineering education. Because this is our main focus, our work is licensed under the GNU FDL license. Users have full rights to reproduce and improve on what we have done, as long as they continue to do so under the same license. We hope that users will improve the design and continue to evolve Helios into a more effective learning tool.

Epilog Challenge VIAn Epilog Zing 16 Laser would allow me to complete higher quality projects, , and increase the amount of impact that I have with interesting large scale things, and to tinker more effectively in general. An Epliog Laser would also allow me to build more interesting things and write more cool Instructables, such as this one about a Kayak that I refurbished. My next goal is to build a kayak from laser cut plywood that is reinforced with carbon fiber or glass fiber, as well as a cardboard surf board that is wrapped in structural fiber.

I’ve also entered this instructable in the Tech and the Teach It contests. If you enjoyed this post, please vote!

Step 1: Table of Contents

Table of Contents:

  • Introduction: DIY Solar Tracker
  • Table of Contents
  • Tools and Bill of Materials
  • Step 1-16 Hardware Assembly
  • Step 17-22 Electronics Assembly
  • Purchasing Links
  • Works Cited
  • Thanks for your Support!!!

Step 2: Tools and Bill of Materials

All of these tools can be purchased at local stores or at the links in the reference section. The total cost of these materials is approximately $80, if they are all purchased online at the given links.


  • Power Drill
  • Drill Bits (.1258”, .18”, and .5” Diameter)
  • Screwdriver Set
  • Straight Edge
  • Box Cutter
  • Large Vice Grips
  • 2 Foam Core Sheets (20” X 30”, ~.2in thick)
  • 9.5” Long by 1/2” Diameter Rod
  • Square Nut (7/16” -14 Thread Size, 3/8” Thick)
  • Vigor VS-2A Servo (39.2g/5kg/0.17 sec)
  • Tape
  • Timing-Belt Pulleys (2), 1” OD
  • Washers
  • Krazy Glue
  • Timing-Belt 10″
  • Templates (Files attached)
  • Mirrored Acrylic Sheet (6” X 6”)
  • Krazy Glue Gel
  • 8 Machine Screws (4-40, 25mm long)
  • 8 Nuts (4-40)
  • 1.5″ long Nails
  • Starter Kit for Arduino Uno
  • Real Time Clock Module
  • Wall Adapter Power Supply (5VDC 1A)
  • 9V battery
  • 3.3 KOhm Resistor (2)

Step 3:

Print the templates in the attached file.

Note: These have to be printed in full scale. Compare the printouts with the PDFs, to ensure that your printer has not changed the scale.

Step 4:

DIY Solar Tracker circuit

Secure the templates to the poster board as shown in Figure 1 and, using the center lines as guides, drill the .18 inch and .5 inch holes.

Note: Drill the .5 inch holes with the .18inch drill bit first for increased accuracy.

Step 5:

With a sharp box cutter, cut out the individual components.

Note: Cut the foam core with multiple passes of the box cutter, this will result in a much cleaner cut. Don’t try to cut through the whole sheet in one pass.

Step 6:

Glue the matching cutouts together as shown in Figure 2, using the super glue. You should be able to look through the cutouts and see that all of the holes are aligned, the base of parts 1 and 2 should be flat, and one template on part 3 should be facing out.

Note: After applying glue to one surface, join the parts and press them together for 30 seconds. Then, allow the glue to set for five minutes.

Step 7:

Using the superglue gel, glue parts 1, 2 and 3 together as shown in Figure 3. Be sure that the parts are arranged so that the .5” diameter holes are closest to the section of the base that is labeled short, also be sure that the template on the base is facing down/out. Allow the glue to set for five minutes. After the glue has set, insert 3 nails through the base and into each of the uprights for added support.

Step 8:

Cut through the top layer of both cross beams and insert them into the Helios as shown in Figure 4. Apply superglue gel to joints between the cross beams and the walls of the Helios, and the surface shared between the two cross beams, as indicated in blue. Allow the glue to set for five minutes.

Step 9:

Place a piece of tape along the cuts, as shown in Figure 5.

Step 10:

Superglue the spacer to the base, by lining it up with the template as shown in Figure 6, and allow the glue to set for five minutes.

Step 11:

Center the largest servo horn onto the bottom base and secure it with the superglue, as shown in Figure 7. Allow the glue to set for five minutes.

Step 12:

Bore out one of the timing belt-pulleys to a .5” diameter hole using the .5 inch drill bit, and check that it fits onto the .5” diameter shaft. It should either press on, or have a gap small enough to fill with super glue. If the drilled hole is too small, sand down the outer diameter of the shaft by hand.

Step 13:

Carefully bore out two square nuts to .5” diameter holes and check that they fit snuggly onto the shaft.



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