Building a solar power heliostat

[Frits] has been working on an solar panel heliostat (in Dutch, check out the translated page here).

The heliostat uses a small PICAXE to control the motor, along with an DS1307 real-time clock to make sure the motors start at dawn. Instead of using optical encoders or magnetic sensors, the angle of the heliostat is measure with a pot attached to the drive shaft. [Frits] did a lot of data collection to figure out that this method is accurate to about 1 degree – just fine for something that doesn’t need to be exact.

According to [Frits] this heliostat will put out 12 to 50 percent more electricity than a fixed panel. Although the build does seem a little bulky, putting it on a  house with a roof pitch of 23.5° would greatly reduce the horizontal profile.

A video of a solar panel rotating at 15 degrees/hour isn’t that interesting, so [Frits] posted a clip of 6 mirrors slewing around fairly fast to demonstrate his system. Check it out after the break.

Comments

  1. password says:

    wow accurate to about 1 degree – *me calculates * – that accurate to 4min of the earths rotation.

  2. fartface says:

    Can be done without all the complexity.

    Why make it timed, make it actually look for and track the sun.

  3. JS says:

    @fartface – good point. why use a complex system when it can be done with simple electronics

  4. Devin says:

    Why make it look for and track the sun when you know exactly where it will be with respect to the earth? The hard work has already been done with altitude/azumith tables freely available online.

  5. steve says:

    >Why make it timed, make it
    >actually look for and
    >track the sun.

    No, thats bullshit. Tracking based on time is extremely accurate as the suns position can be predicted exactly. Measuring it induces error and wastes power if clouds make it jiglle back and forth. Timed is the only way to go!
    The build looks nice, but I don’t understand, why those people building these never consider the outdoor environment. This wooden thingy will just rot and rust and be broken apart by the wind.

  6. K!P says:

    about the wood build: i think its a proof of concept? also: wood that is threated well can easily last 15-20 years, and is was greener to produce than some shiny aluminum extrusions.

  7. Nefario says:

    Call me stupid but wouldn’t it be more convenient if the panels weren’t mobile at all?
    If it was instead some sort of collector (satelite dish covered with a reflecting material) that would track the sun?

  8. Toolboy says:

    Not a heliostat, that’s what we in the biz call a one-axis tracker. A heliostat is a device used to reflect sunlight onto a target (like in Concentrated Photovoltaic applications). Heliostat sounds cooler, I’ll give you that…

  9. fartface says:

    Steve is such a professional idiot. Hi Steve!

    Too bad systems like what I am talking about is used in industry, and his claims are based on his lack of experience and wild ass guessing.

  10. mungewell says:

    Without a doubt you can get more power by tracking the sun, however it does have it’s issues.

    # More complicated system, thus more to fail
    # More delicate system (I happen to live in a fairly windy area and was concerned that a cheap mount would break and damage an expensive panel)
    # The majority of the gain comes in the summer when (if off grid) it is not required.

    Even if you are tracking, towards dawn/dusk you may not be producing enough voltage to be able to charge. I would suggest people series up the panels to a higher voltage and use a MPPT charger (to squeeze the twilight power out) before spending on tracking mounts.

    BTW I have an off-grid 1.3KW system in Southern Alberta.

  11. AussieTech says:

    @fartface – think about it, clouds &c.

    More like 10% than 30%, and still pointless unless you have a whole field full of panels.

    Energy loss is proportional to the COSINE of the angle of incidence folks.

    @Nefario – panel manufacturers specifically warn against using reflectors or concentrators.

    @fartface is such a professional idiot with his wild arse guessing. Some of us really have got industrial experience and know why time tracking works better, but tracking generally only makes sense with industrial scale installations because of the COSINE factor. @Steve and @mungewell are on the money. I can vouch for the effectiveness of switch-mode Maximum Power Point Trackers in on-farm water pumping applications.

    Hi Fartface – your first comment marks you as a know-nothing troll.

  12. Whatnot says:

    Here we go again, acting like throwbacks, fartface linked to an actual working hack and although the clouds arguments is good since holland is pretty damn cloudy people have to push it to a fight and then start throwing the ‘troll’ remarks around.
    Why not also throw in the nazi remark and end the thread while we are at it?

  13. RB says:

    A simple way to use solar tracking is to use a photovoltaic switch which gets turned on/off by an arm attached to the panel which casts a shadow. The switch controls a little motor… err u know what i mean

  14. sssalvi says:

    Sorry .. for being a latecomer.

    The concept of coupling multiple panels to single drive is nice. Only thing is power( I mean total system of motor, gears ) for driving a large panel may not allow the use of simple drive shown.

    BTW ask any supplier for incorporating tracking and they say it is impractical. ( complicated /bulky/ difficult to maintain and so on )

    I think it has more to do with economics .. more efficient system means less number of solar panel sales.

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