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!