First Bigish Project: Sun tracking solar panels.

[Grompus]

Hey, my first post so go easy on me. :wink:

I am reasonably new to electronics, having only really taken an interest in the last few months. I have purchased a good book on electricity and electronic theory and think im starting to understand how things are thrown together.

Ive built a few basic kits (the classic LED torch, solar generator ect.) and have been giving a bit of thought to a bigger project. I'm quite a mechanically minded person and thought of something I would like to attempt: a sun tracking solar panel.

Basically I have a small dual motor gearbox (208:1 ratio, nice and slow) with dual shafts (independant) and was thinking of an application for it. Basically one of the shafts would control the side-side movement, with a wheel traveling around a base pivot, and the other would control the angular movement of the pannels with some kind of lever.

So it would have some kind of photsensitive diode array (or something else that can detect changes in the suns position) and drive the motors according to the change in location. Im not too familiar with the constraints or sensitivity of these sorts of things and am still trying to think of a way to actually use them. Would having the sensors in the shadow of the pannel themselves work? So that when the sun travels past the pannel and the sensors come out of the shadow into direct sunlight they can trigger the motor somehow?

Anyways besides the point a bit - my main question is this:
Does this project sound a little too complicated for a beginner?

I havent had experience with any IC's yet, but do have a little programing knowledge. My understanding is that this would require the use of some sort of programable IC with timers and all that jazz.

Thanks.
-Tarant

 

[Klaus]

Hi Tarant,
That does sound like an interesting project. Have you searched the net to see how its done on commecial units? I'm sure Google would turn up lots of info under 'solar panel trackers'. I've even heard of passive methods where the sun warmed up some liquid in tubes and somehow altered the panels orientation from that.
With active tracking you will have to calculate if the energy required for the tracking motor(s) is less than the extra output gained from doing that. Else, your efforts may amount to no gain or even a loss with respect to fixed panels.
I've seen lots of solar panel arrays in the outback of Australia, powering communications equipment, but they always seem to be the fixed panel variety. Tracking panels are more common on large solar 'energy farms', perhaps there is a good reason for that.
One also has to consider the wind loads which could be considerable since panels have quite a large area and weight. Hence your mountings have to be very secure yet low friction to get away with small motor power.
Perhaps that is your biggest hurdle, the electronics for tracking should be quite simple after that :wink:
Klaus

 

[I am a fish]

Such a device could be greatly simplified by using an equatorial mount. Instead of moving the panel in two dimensions, you could mount them on a single axis tilted so that it's parallel to the Earth's north/south axis. Using a system like this, the sun can be tracked just by rotating the panel at a rate of one revolution per day. The Sun is always less than 22.5 degrees from the Earth's equatorial plane, and so the light collected would always be greater than 90% of the maximum possible amount.


Chris

 

[losfromla]

Moveable array a tough order

I agree that moving the arrays is most likely not worth the cost and required energy for the motors. You probably as mentioned earlier want to somehow split the difference between the sun's max and min declination according to your latitude. Keep in mind that the sun is closest to the earth when it's declination is the lowest (about 23 deg south), so you may adjust you solar array's angle to get the best power on average year-round. Maybe you could have some reflectors that don't move but allow you to concentrate power during peak sun hours or something... but that is mostly a solar power discussion.
If you want to just track the sun, I would suggest a tube to direct light only onto a few photoreceptors and use the differential power received to drive your control circuit and rotate your tube. Being a newbie I've no idea how you would do this electronically.

 

[ashton86]

gday grompus,
im reasonably new to all this as well and am interested in the title of the book that you purchased.

I would imagine your project has well and truely been completed by now and i would like to hear how it went and what you finally decided to set up.

i have been considering setting up a similar tracking device. Ideas that i have thought about include a simple motor that is set on a timer. through out the day the motor simply rotates the panel rather in time with the movement of the sun. of course this isnt exactly perfect, especially as the timing and position of the sun changes throughout the year. however, it would take out the complexities of a tracking device.

my idea is to place the panel on a pivot, the motor is low geared and turns on in the morning slowly panning the panel the 180degrees throughout the day. at night the timer trips again to reset the panel awaiting the next mornings sunrise.

What do you think?

Cheers, AShton

 

[rjvh]

have a look at www.redrok.com i buid the led 2 tracker and it works good sometimes it hunts a little but the set up is ok
the electronics is not the hardest part mechanical is much trikyer to get it perfect
i am also a skilled mechanical person and still had to spend some time in it
especialy if you build to last it means taking the right materials for the conditions (hot weather or cold weather or both)
don't forget the birds that can sit on it (or snow) not woryfull if your panel is 1 sqr meter but if you have 12 sqr meter can be a different story
other advise is make a mechanical stop also and not only an electrical one

sucsess
Robert-Jan