There has been a bug fix for the Arduino Sun Tracking / Heliostat program, Ver. 0.9.2.

For the newest version of the program, I moved the hour angle table into flash using the Program Memory library. The new table was working when I did the main testing on it, but I guess it decided to start spitting out incorrect values when I re-wrote other parts of the program.

The values were correct for May when I was doing my initial real life testing but have been drifting further and further off ever since. I didn’t notice because my own heliostat has been off until I find something useful to do with the excess heat energy during the summer months.

Anyway, I fixed it by using a different Arduino library called Flash which is quite a bit less confusing to use and is also supposed to be less buggy then the Program Memory library.

Please note that you will need to download and install the library for the updated program to work. http://arduiniana.org/libraries/Flash/

Also, a big thanks to Jim on the forums for noticing the bug.

If anybody notices any other issues, please let me know. Thanks!

This page will show you where to put the reset limit switches on either a heliostat or a sun tracking machine (both are set up the same way). Although this page has been written with the Arduino Sun Tracker program in mind, the general concept should be the same if you happen to be using another similar program.

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After a mind numbing amount of work to rewrite massive sections of the code, here is the finished update to the Arduino Sun Tracking / Heliostat program. The improvements include the following:

To start, the table which contains the hour angle values has been completely redone. After a bit of research, I learned that it could be moved into program memory, thus giving it enough space to hold values for every day of the year. This means that the calculated altitude and azimuth values of the sun are more accurate now that the table doesn’t skip days.

Much effort was put into making the program more user friendly. In particular, adding more machines is now a lot easier than it was before. The process now only involves editing a couple of lines of code where as before it was just a horrible mess of copying and pasting.

The code for controlling the stepper motors has been consolidated into a function named “moveToPosition”. This makes it much easier for someone to modify it for their purposes.

Fractional steps are now saved and added back in during the next machine update. This keeps steps from being lost due to rounding error.

There has also been a few bug fixes and a general cleanup of the code to make things more readable.

In general, I’d say that the core program is about as finished as it is ever going to be. It is, however, certainly possible to add more features around it. If you add anything, please feel free to share it on the forums. Also, let me know if you run into any new bugs.

Thanks!

On this page you will find a program for the Arduino which is capable of controlling various types of solar machines. For example, it can be applied to a dual* axis solar panel tracking system, a parabolic dish solar concentrator, or any other type of machine which points directly at the sun.

This program is also able to control a heliostat with multiple targets programmed into it, each available at the flick of a switch.

In fact, it is able to control all of these different types of solar machines simultaneously from just one single Arduino. Continue reading →

When setting up a heliostat, it is necessary to select a target for it. This target is simply where the reflected light from the sun stays continuously throughout the day. It’s a fairly straight forward concept, but it can be a little difficult to visualize. To help make things clearer, this page contains a handful of pictures along with a few quick paragraphs to explain what’s going on.

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