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NETMF solar tracker


#1

I scrounged a bunch of small solar cells from some KMart variety lawn lights and am hoping to make a panda sun tracker with the Connect sheild and a couple of small servos. If I’ve done the math right, I think I can post the data online with pure (bright) sun power. A 2 cell LiPo and the roughly 8v trickle the from the solar cells hopefuly will do the trick. The idea would be to have the FEZ ‘hunt’ for the max output from the panels on a fairly frequent schedule, remembering the results.

Done something (even vaguely) like this before? If so, let me know!

Eric


#2

i’ve seen it done on a larger scale (real PV installations), but the theory is the same.

Most people use an algorithm based on the actual (accurate) time and the known geolocation, and calculate what the direction should be. Otherwise, you can get into a situation that the “cost” of tracking (running the servos) is too great for the benefit that the tracking gives you. Purely “hunting” can quickly negate the benefit that you get.

I’ll watch your project with interest. Somewhere in the future I have a solar project on the cards (remote one-wire weather station) and if you can get tangible benefit here it might be something I do.


#3

Ive done a simular project.
For the algoritm you can use SPA
http://www.nrel.gov/midc/spa/
or SOLPAS
http://rredc.nrel.gov/solar/codesandalgorithms/solpos/

If i was u i wont be using servo motors you need motors that doesnt consume energie when they are in a locked position

I hope this helps


#4

That would be fun making a mobile device with a GPS for getting the position and a dual-axis compass module for knowing its relative position. Wherever you go, you just drop the device, and it’s handling ervything :smiley: Hum, costly for a few watts !

At home for a fixed solar station, after studying a bit the question, I decided to set a fixed angle for the water heating solar panels, the ratio complexity-fiability/powergain was not winning with too much mechanics :-[ I just over sized the panels by 25%…


#5

Thanks for the feedback. The idea is to get a 2 cell LiPo to recharge reliably so I can stop fretting over how much juice I have left when my Panda is outside (I’ve resorted to a long extension cord). Tracking the sun horizontally is supposed to give me roughly 30-40% more ‘max charge’ time. Vertical angle adjustment is not worth the effort.

I’m attempting to keep track of temp in a recently built coldframe (DIY mini greenhouse). The Panda is giving me an idea of the temperature variance inside this wood and plexiglass box. My starter veggies need to be “hardened off” a few days in this before being planted. Too hot or too cold and all my indoor germination efforts end up in the compost.


#6

@ Nicolas3, that is exactly what I’m doing using a GPS and digital compass, indeed its costly but the project is fun. Folowing the sun is required for CPV (Concentrating Photo Voltaic).

Marcel:
http://Your2Power.com


#7

[Update] The solar cells I scavenged were in pretty bad shape. I got just enough current to light a couple LEDs. It’s time to invest in some cells that give me the juice I need…