Portable two-axis manual solar tracker

Solar tracker in front of my camp at Burning Man

Last year, I took my beloved Engel fridge/freezer with me to Burning Man, but had trouble keeping it powered when my generator died. So this year, I decided to run my camp off of the new 100 Watt solar panel I’ve been using up on my property for a couple of weeks now. While my fridge only uses less than 10 Watts of power, I wanted to try and build a solar tracker to maximize output on my property, and Burning Man seemed like a great place to test such a device.

In order for the tracker to be useful on my property, I needed it to rotate around two axes: one to track the sun during the course of a day, and the other, the elevation, needs to be adjustable since the sun tracks higher or lower in the sky depending on the season. Additionally, in order for me to bring it to Burning Man, it had to be easily transportable, yet also be able to withstand up to 70 mph gusts in the desert.

The general design had been bouncing around in my head for a while now, and is based loosely on a giant tilt maze game I made a while back. To lock things in place, there are two half-disks attached to each of the rotating pieces, which are locked in place using a pin. The whole thing is held together with 1/4″ bolts, and can be assembled or disassembled within minutes by one person. And, as you can see below, it all comes apart into relatively flat pieces for easy transportation. To save weight and bulk, I also used more 2x2s and 1x4s instead of 2x4s, and I mostly used scrap wood I found lying about. At Burning Man, I put my AGM battery, which weighs about 60lb, on one of the legs, and when particularly strong winds were forecasted, I put one of my water cubes (also 50lb+) on one of the other legs. I had the tracker oriented south, and moved it roughly 3 times a day to catch the morning rays from the east, mid day sun from above, and afternoon light from the west.

All in all, it worked very nicely, and I’m happy to report that it fulfilled my requirements perfectly.

13 thoughts on “Portable two-axis manual solar tracker

  1. Hi,

    Question: Have you compared the output of your solar panel as is to the output when you only have it tracking the sun on one axis?

    I’m wondering if there’s a huge difference. Or if you know from others/research that it does/not make a huge difference.

    Please/thanks!

  2. On the one hand, this is cool. But….

    It seems to me to be a rare combination of underkill and overkill.

    Overkill because a couple of sticks and a rock could have propped the panel at almost any angle.

    Underkill because if you need to realign the panel by hand, then it needs babysitting all day, which is all right if you are just chilling out, but which is seriously limiting if you have other stuff to do.

    I once considered putting a sun-sensor and servos on a skylight louver to maximize solar heat gain, but I moved instead. I wonder how hard it would be to hook up some threaded rod and stepper motors to automatically track the sun, no alignment worries – just plunk it down and plug in.

    • Actually, I think the difference between moving the tracker a few times a day vs not at all, is much greater than the difference between moving it a few times a day and tracking constantly. So, IMO, what I have is worthwhile, but I’ll need to get some numbers of back up my intuition 🙂

  3. This device:
    http://en.wikipedia.org/wiki/Solar_tracker#Passive_tracker
    makes it easy, a friend of mine had one for a while before he put in a huge system.

    Not sure they are worth the extra watts, considering the cost. I suppose if you are barely squeeking by, adding a few more watt hours might be worth it.

    But realistically, I think a small clock type tracker is more than enough and easier to make yourself, especially if you don’t mind resetting it every day. Heck, you could probably make one like an old mechanical clock.

    Bob L

    • Thanks for the link. The idea I’ve had kicking around in my mind is similar to the concept explained in the latter half of the section on passive tracking. I was thinking of getting a cheap low res CCD, cover it up with cardboard (or similar) with a tiny hole in the middle, with some space between the CCD and cardboard. A small beam of light will shine through the hole in the cardboard and hit the CCD, and depending on where on the CCD the light hits will I can calculate how far from “center” the panels are pointing (basically, the panels and CCD sensor needs to be rotated until the beam is centered). I guess this is much more complicated than the version that uses expanding gases though 😛

      • Heck, you could get a couple of weights, make a few gears and have a grandfather clockworks style tracker.

        You know where the sun will be when. A motor and a timer would be simpler and will probably work better than anything.

  4. Thanks Ryochiji,

    Your response was exactly the type of information I seek. I suspect the same but of course have no way to test the theory. Please post any future experience on this topic if you can.

    If thinfilm solar makes it into the RV market soon it won’t matter but if not I could use the knowledge in my purchase decisions.

    Thanks!

  5. Pingback: Journal: October 1st, 2010 « Laptop and a Rifle

  6. A friend just sent me this link to a guy who made his own high quality solar panels. His need was that where he was, getting solar panels was EXPENSIVE, but he was able to make his own for a reasonable price and had fun doing it. You or one of your readers might want to contemplate this project for some time in the future. The site also has wind and other power projects.

    http://fieldlines.com/board/index.php?topic=145005.0

    Bob L

  7. Pingback: Solar Tracker Experiment « Laptop and a Rifle

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