two axis solar tracking system

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SolarPulse
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Re: two axis solar tracking system

Post by SolarPulse » Tue Feb 10, 2009 8:14 pm

Hi everyone, one more question...

in my prototype, im using a 10W solar panel which weighs 1.5kg. how can i select the best stepper motor which would drive this without any problem?

lets say the pivot is at the middle of the solar panel (dimensions: 36 x 31cm). my solar panel is charging a battery (12V/5Ah).
now the power for the motors/sensors and any circuitry will be supplied through the battery. so i am assuming 12V stepper motor would do the job, but the current is the problem. im planing to move the panel 15 times per day. so i would only power up my motors and sensor, only when i want to move the panel. ( i will use worm gears to increase the holding torque of the motors so there wont be any movement ones the motor power will be switched off. if anyone can please help me decide the best stepper motor specs, that be a great help.

cheers!

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SolarPulse
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Re: two axis solar tracking system

Post by SolarPulse » Tue Feb 10, 2009 9:02 pm

hey guys its me again. can you tell me if the calculations bellow are right?

my battery is 5Ah. which also means a 1A current will charge it in 5 hours. Now since my solar panel is 0.58A, the battery will take about 9.5hours to fully charge provided the solar panel outputs 0.58 for the whole 9 hours. this means on a typical clear day the solar panel would charge the batter in a single day?

Then, if i use two 12V(0r less), 2.3A stepper motors, my battery can supply current continuously for 5Ah / (2x2.3A) = 1.087hours.(?) now since i only power up the motors 15 times a day for 1 minute each(say), I would draw 4.6A x 0.25 = 1.15Ah for the whole day. is this right? if it is right, does this mean that, i can still have plenty of power from the battery to power up the circuitry and sensors?

thanx

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jwax
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Re: two axis solar tracking system

Post by jwax » Wed Feb 11, 2009 2:34 am

Solar Pulse- In general, those calculations are accurate, but let me quote the following: "Your actual performance may vary". You can't compute all the variables, so the worst case is that your 5 Ah battery isn't sufficient for your installation, and you may have to add more capacity.
Keep in mind also, that the elevation motor need not run very much at all. Maybe only once a day, if that.
Also, the efficiency of your solar charge controller has to be considered, but they're generally not a big issue.
Some of us would like to see some pictures of your installation when complete! :grin:
John
WA2RBA

dyarker
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Re: two axis solar tracking system

Post by dyarker » Wed Feb 11, 2009 8:33 am

If the weight of the panel and supporting frame work is balanced at the pivit points, then the motor only has to overcome inertia and friction; then the motor may not need the whole 2.3A.
Dale Y

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