solar tracker pondery, for small systems.

bmet
bmet Solar Expert Posts: 630 ✭✭
in General Solar Power Topics #1
I read some of the tracker discussion here, and googled the subject trying to understand how the mechanical control happens. So far, motors are the preferred device to move an array.

But I was curious if any other methods were less susceptible to wear, like maybe a hydraulic or pneumatic system. Hydraulic pistons can be small and still move a lot of weight, and their psi doesn't have to be high. How much movement could one get if an array had a small piston on each corner, and a microprocessor used 4 photoresistors instead of two(4 points of the compass). A small pump feeding 4 valve actuators, could raise or lower each corner in small increments according to a null result of the light detection circuit.

just asking.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #2
    Re: solar tracker pondery, for small systems.

    Thinking along the same lines.

    Pneumatic systems in the NE would have water/freezing problems. Plus one would need to pressureized both sides of the pistion to avoid any movement during wind.

    Hydraulic maybe a good solution.

    I was thinking of a simple system that you pump/lift the array up in the morning. Then using the weight of the array, bleed it down to track the sun.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #3
    Re: solar tracker pondery, for small systems.

    The idea is intriguing. Would you or use a swing-arm, or a ram? How could the bleed-off be managed without discharging too much?
    n3qik wrote: »
    Thinking along the same lines.

    Pneumatic systems in the NE would have water/freezing problems. Plus one would need to pressureized both sides of the pistion to avoid any movement during wind.

    Hydraulic maybe a good solution.

    I was thinking of a simple system that you pump/lift the array up in the morning. Then using the weight of the array, bleed it down to track the sun.
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  • n3qik
    n3qik Solar Expert Posts: 741 ✭✭
    #4
    Re: solar tracker pondery, for small systems.

    I have a 4" x 24" ram that was looking at using. Bleed off would be controlled by electric valves.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #5
    Re: solar tracker pondery, for small systems.

    If one were to go with some sort of pivoting, or hinged support, another device which could move the array without regard to pressure or temperature, would be an electric gate(long screwjack), turned on end. It's battery operated, and solar powered.

    I recently bought a used Apollo 1500 system for $800. It can pull gates that weigh 300 pounds. With some timer circuit added, it could turn on and off for short durations throughout the day.

    Granted this idea is far fetched, but is an almost ready-made tool for smooth movement of heavy loads.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #6
    Re: solar tracker pondery, for small systems.

    i think there's a better deal to be had with using old c band satellite dish arms if one wants to move the array, but without automation.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #7
    Re: solar tracker pondery, for small systems.

    I don't know satellite dish stuff. Is there are large market for that? At least with electric gate openers, they are tens of thousands of them in use across the country, so someone always has parts.
    niel wrote: »
    i think there's a better deal to be had with using old c band satellite dish arms if one wants to move the array, but without automation.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #8
    Re: solar tracker pondery, for small systems.

    it was a fad by many in the 80s when satellite services weren't scrambled or scrambled as much and many are still up and could be gotten for a song, but you may need to take the dish with it too.
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  • bmet
    bmet Solar Expert Posts: 630 ✭✭
    #9
    Re: solar tracker pondery, for small systems.

    What is the loading capability of these satellite 'arms'? Aren't the dishes themselves very light in weight? I would think that putting 3 or 4 panels that weigh in at 40ish pounds each PLUS the weight of mount/wires/, might be a tad more than a parabolic dish?

    Or am I talking out my butt?

    niel wrote: »
    it was a fad by many in the 80s when satellite services weren't scrambled or scrambled as much and many are still up and could be gotten for a song, but you may need to take the dish with it too.
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  • arkieoscar
    arkieoscar Solar Expert Posts: 101 ✭✭
    #10
    Re: solar tracker pondery, for small systems.

    Back in the mid 90's someone was making a system that used a freon filled ram that was powered by heat and tracked the sun. When it cooled down, it returned to the east. I can't remember who made it but it was sold by (I think) our host's predecessor.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #11
    Re: solar tracker pondery, for small systems.

    are you thinking of zomeworks?
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  • arkieoscar
    arkieoscar Solar Expert Posts: 101 ✭✭
    #12
    Re: solar tracker pondery, for small systems.

    I don't remember the name and I lost paperwork in a fire after that but I considered it for a pole mount with 8 kyocera panels on it. I went with an electric system (using a screw) that lasted a couple of years before being more trouble than it was worth to repair. System is still in operation, just pointing south full time.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #13
    Re: solar tracker pondery, for small systems.

    Here are a couple threads that discuss Solar Tracking Systems and some recommendations:

    Eletrician Going Off Grid - Sizing / Questions
    RedRok Solar Tracker

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • XRinger
    XRinger Solar Expert Posts: 529 ✭✭✭
    #14
    Re: solar tracker pondery, for small systems.

    An old satellite dish mount can be made to work, but if it's the standard
    sized dish (8-10 ft diameter), then you are going to be limited to about
    200 pounds of PV & rack..

    Here's my 500w array.. (and, it's sordid history).
    http://ecorenovator.org/forum/solar-power/875-solar-tracker-project.html

    bolted4.jpg

    I think it's total weight (of the moving parts) is about 140 pounds.
    I ended up using the RedRock tracker board (pre-built) and it works very well.

    Depending on how far north you live, you may be able to find some jumbo sized dish rigs, that will support a lot more weight.

    Or, you can copy the Polar mount design and make your own heavy duty mount.
    If it's balanced well, a large dish mover (actuator) should work okay
    and last for at least a few years.

    The elevation on mine is done manually, every week or five, takes about 45 seconds.
    By not installing a Y-axis motor and controller, you save money and have less things to break down.
    And manually tweaking allows you to get some fresh air once in a while.. :)


    Cheers,
    Rich

    http://www.youtube.com/watch?v=YiseTYV-LZ8
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  • Peter_V
    Peter_V Solar Expert Posts: 226 ✭✭✭
    #15
    Re: solar tracker pondery, for small systems.
    bmet wrote: »
    I read some of the tracker discussion here, and googled the subject trying to understand how the mechanical control happens. So far, motors are the preferred device to move an array.

    But I was curious if any other methods were less susceptible to wear, like maybe a hydraulic or pneumatic system.
    just asking.

    You might want to look into the Zomeworks style trackers. No motors, no pumps, no electronics of any kind.

    They just have two cylinders on each side of the array full of fluid with a very low boiling point (Zomeworks uses Freon but you can use propane or several other fluids). The cylinders are connected by a thin tube. The outsides of the tube have shades on them so the sun can only shine on part of them. When the array is facing the sun then both cylinders are equally exposed and at the same temperature. When the sun moves, the cylinder on the east side is exposed more and temperature increases and this increases the pressure in the cylinder forcing some of fluid into the cylinder on the west side. This increases the weight in the west side and the array tips to face the sun again.

    Simple and reliable, virtually nothing to wear out.

    This shows the array without the shades installed, the thin line going from one side of the array to the other along the front is the tube connecting the fluid filled cylinders.

    Panels_Install.jpg
    The black thing hanging below the left side of the array is the "wake up fin" it's used to heat up the west side cylinder in the morning and force all the fluid back into the east side to get the array to flip over and face the morning sun.
    That's about the only down side of this type of tracker, it takes about 45 minutes in the morning to flip over and face the sun so you down produce much power during this time.

    Here it is with the shades installed (shiny bit on the front)
    Panels.jpg
    The shades shadow about 1/2 of the front of the cylinders when the array faces the sun.

    I'm working on a webpage describing how I built one of these trackers, but so far all I have up is the photos
    http://www.vanderwal.us/Solar/DIY_Tracker.html
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  • XRinger
    XRinger Solar Expert Posts: 529 ✭✭✭
    #16
    Re: solar tracker pondery, for small systems.
    bmet wrote: »
    What is the loading capability of these satellite 'arms'? Aren't the dishes themselves very light in weight? I would think that putting 3 or 4 panels that weigh in at 40ish pounds each PLUS the weight of mount/wires/, might be a tad more than a parabolic dish?

    Or am I talking out my butt?

    Some of them are aluminum wire mesh. Mine was, and I think it was only about 70-80 pounds.
    But, you have to remember, the mount has to bear the wind load, and any snow load.

    Once when I was doing radio astronomy with my 10.5' dish, I left it up in 'bird-bath' mode by accident.
    We got and unexpected snow storm and the dish filled up with heavy snow.
    Must have been about 500-600 pounds in there!
    It was a bit off balanced, and it Dumped, by bending a very heavy steel angle iron..
    When the weather cleared, it was repaired and back on the air in no time.

    Some of those 10 to 12 foot fiberglass dishes are a lot heavier than mesh.
    Those mounts are beefy.. Maybe a better choice than light mesh mount like mine.

    Cheers,
    Rich
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