Heliowatcher positions solar panels for highest efficiency

[Jason Wright] and [Jeremy Blum] are showing off the project they developed for their Designing with Microcontrollers course at Cornell University. They call it the Heliowatcher, and if you know your Greek mythology we’d be you figured out this watches the movement of the sun and adjust a solar panel to follow it.

Their design is simple and effective. The base is mounted like a Lazy Susan, able to pivot on the horizontal plane. The bottom edge of the solar panel is mounted with two door hinges, with a motorized screw jack used to raise and lower it. The system uses a GPS to provide geographical position, day, and time feedback. This is used in conjunction with an array of four LEDs to determine the best position of the panel. Those LEDs are acting as light sensors; when the top and the bottom detect similar levels, the panel is at its most efficient orientation. The left and right LED sensors work the same way.

Now if we can just work out a self-cleaning system to keep the panels free of the dirty film that builds up over time we’d be set!

Comments

  1. Kendall says:

    Nice looking project. I am sure you all got a awesome grade. However from a real world prospective, I imagine that you could drop everything but the moving parts, microcontroller and leds. Then just use the leds to determine where to point as it won’t matter where it is if a tree is in front of it. Like I said, Great project.

  2. adcurtin says:

    The idea is good, but this implementation is unusable. The jack rubbing the back of the panel wouldn’t work, but that could be solved by making a mating adapter from the jack to the metal frame of the panel. The jack was a great idea, and will be plenty strong enough. The friction holding the rotation in place won’t work in any amount of wind, change that to something else that will stay in place, and this is excellent.

    • jpwright says:

      Jason, one of the creators, here. The jack actually worked quite well with no additional attachments, with no damage to the back of the panel. An accelerometer also corrects for any slippage. We considered adding something to make it slide easier, but were pressed for time and limited to a $75 budget for our class. (A larger rotating platform than the one we built could also solve this, as you could mount the jack further from the hinges, reduce the load at low angles, and attach it to the top of the panel with a cord.)

      As for the rotation, I’m not sure how much it would be affected by wind — stepper motors have pretty good holding torque, and we gave the wheel a ton of traction since the panel & jack combined weight is pretty high. We didn’t get a chance to test it in a windy setting, though, so it’s a fair concern.

      • nes says:

        Very nice presentation.

        I think you could maybe have looked at using car seat actuators. They work the same as the screw jack you have but use a high-torque DC motor and gearbox to drive an acme thread which in turn slides a nut in a channel.

        High-end vehicles with seat position memory already have the feedback pots built into the actuators which means you just need to add an H-bridge driver to turn them into a servo.

    • Goumas says:

      I think this is more of a proof of concept rather than a production model. That’s usually how it works for class projects.

  3. ” self-cleaning system” -> why not a light powered BEAM robot with cleaning feet, magnetically strapped to the panel wandering randomly on the surface?

  4. Galane says:

    Nice setup for getting a good grade on a project, but most of the sensors etc aren’t needed at all.

    For the LED light sensors you can mount two pairs with a vertical sun shade between them. Have one for altitude and one for azimuth. There’s fairly simple circuits to take input from the LEDs and aim the panel simply by moving it towards whichever LED is putting out less voltage then stopping when they’re in balance.

    For end of day you can have it setup to run the azimuth actuator all the way back to the east when all the inputs from the LEDs go to zero (it’s dark) or below a threshold value.

    Such simple systems have been in use for years. Look up homepower.com

    Old big dish satellite TV mounts are excellent for this because they already have an azimuth actuator with position sensor. Just add an altitude actuator and the mount is ready to attach a big PV panel.

    For the setup you’ve built, refine it so that it has only what it needs, all on one circuit board, and you’ll have a “drop and forget” boutique solar power setup for people who drive big motorhomes. Just plonk it on the ground, plug it in and the thing “magically” points itself at the sun and tracks it. Combine it with a monitoring panel for inside the RV and the campers will love it. Then do a “minimalist” system that works just as good but has to be pointed in the general direction of the sun to start. No GPS, compass, temperature readout or clock, just solar power.

    Equip it with some fast motors and it could be used on boats for rock steady positioning. There are already such mounts for DBS TV dishes on boats.

    • sciguy14 says:

      Again, this was put together in a few weeks for a final course project. There was not time to custom-make a PCB, or to implement everything we wanted to. So, we designed the system as a development platform in the hopes that other would be able to benefit from the elegance of the system that we created.

  5. thereeducationof says:

    This is really elegant.

    I worked on something similar, if a little cruder, to compare static, 1DOF and 2DOF tracking for poly-Si for my masters dissertation. It uses a similar 4 LED approach for tracking without the GPS element to save on power usage.

  6. bryan says:

    Cool. what was the net power increase for having direct sunlight over stationary roof mount? Is it a positive or negative after running GPS, processors and motors.

  7. Mike says:

    There are a lot of good ideas here, where can a buy a reliable tracker?

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