Build a mini solar tracker

[izentrop]

manual height adjustment once a month, and rotation at constant speed starting at a fixed time .... return to the end of the race overnight .... to be sure that the return to the end of the race takes place the direction reversal time is a little before 6 p.m. solar time

An automatic system that requires manual intervention ... BOF !!
If it does the trick, unnecessary power consumption during the night phase and we can not fix it against a south facing wall ??

I found small 3 V electromagnets at 2 € and dust. Just spin a perforated disc.
The electromagnet releases its rod in one of these holes at each positioning, locking the mechanics. Programming does the rest.

[dede2002]

Hello,

In my opinion there is no need for great precision, in 1 hour the earth turns 15 °, the cosine of 15 ° is 0.97, there is still 97% of the active surface after 1 hour. After 2 hours (30 °), 87% remains.

By adjusting 15 ° each hour we have about 1,5% losses, compared to a continuous plotter.

My idea would be to use a wiper motor transformed into a capstan, which moves the panel in small pulses, controlled by small pv in the shade of the large pv, and relays. (I will make you a drawing )

For the azimuth it varies from 46 ° in 6 months, there is no need to change the angle every day.
Doing it manually during an inspection or cleaning may be sufficient.

[Gaston]

with an equatorial mount you can adjust manually to adapt to the height of the sun ...

Yes.
I offered 4 times a year ...

and rotation at constant speed starting at a fixed time ....

This is the point that "bothers" me the most: at each shutdown (maintenance, safety, etc.), you have to wait for the right time to restart (or place yourself in the right position corresponding to the restart time) .

[Villegente]

Hello,

Thank you all for the information you provide.
I have a question concerning the solutions to an "automatic" axis. If there is no human in the area. How to put the panel in the safety position automatically? With a 2 axis system I see, but with 1 single axis controlled.

We look forward to seeing you!

[chatelot16]

why put it in a safe position?

the stuff has to be strong enough to withstand wind and weather in any position

in order not to waste power, the slewing motor must be slow: it will not be enough to bring the thing back to a position quickly in the event of a wind alarm from an anemometer ... you must rather be satisfied with taking measurement protection manually in the event of an exceptional storm announced by the meteo

an electro magnet for a blocking system is useless: given the huge reduction ratio it takes to go from the speed of an electric motor to 1t / 24h it will be inevitably irreversible

in the event of restarting after a breakdown, if we do not want to wait for the restart in the right position the next day, we can provide a possibility of declutching somewhere in the transmission to put the thing manually in the right position

[izentrop]

My idea would be to use a wiper motor transformed into a capstan, which moves the panel in small pulses, controlled by small pv in the shade of the large pv, and relays. (I will make you a drawing )

The idea is good for an already larger panel, the reducer brake should be enough to prevent the wind from disturbing a panel of one or 2 m².

Since I don't want to bother with an equatorial axis, I would see a system with 2 recovery wiper motors mounted directly (without capstan), controlled by an arduino-style automaton, a sensor with 3 photoresistors , 2 H bridges with mosfet to pilot the motors in both directions. Repositioning every 1/4 hour or 1/2 hour if the motor consumption (~ 30 W) is a problem. It is especially the price of the engines which will determine the cost of the thing

Ps: No intervention of the blows.
Also provide for an automatic return to the EST orientation at nightfall and rest until daybreak with a minimum light threshold. Photoresistors giving the necessary info.

[Grelinette]

Hello,

I bring my stone to the building of this project, or my grain of salt, it is according to the opinion of each! ...

For my DIY that requires a regular movement or a frequency, I use the small mechanical watering programmers which offer pre-settings (in frequency and duration), and can be easily diverted from their intended use by a small mechanical DIY.

In this case, once we have determined the frequency and duration of watering, there is a small mechanical valve that turns 1/4 of a turn at the opening (frequency), then another 1/4 of turn on closing (duration), and the reduction of which is significant enough to cause a mechanism either door opening or hatch, or to rotate something.
It's still plastic but quite resistant and by adapting this type of programmer to a more solid mechanism, I think we can train a much heavier object.

This type of product costs 20 to 30 € depending on the quality (or brand), works with 2 small 1,5 volt batteries, is waterproof against rain and humidity, the hourly accuracy is very correct (I tested), and the autonomy is about 1 year but you can easily add an additional battery pack for more autonomy.

I have just recovered this one, and on reading the technical proposals, it seems to me that it can be suitable for a mini solar tracker with a suitable choice of frequency and duration which each time produces a rotation of 1 / 4 turn of the ball valve:

I indicated in yellow the direction of rotation of the sphere and the red point indicates the axis.
Fixing a small pulley on this small sphere is simple, with possibly an additional reduction to have more torque.

It remains to find the right combination of frequency and duration for the rotation of the sphere exactly following the movement of the sun in steps. I haven't thought about it yet, but if someone finds it instinctively, I will test to tell you if the rotation of the sphere follows the sun!

[Grelinette]

Hello,

I come back to my previous comment to ask you for confirmation on a small reduction calculation ... it is a priori simple, but I stumble on the reflection ... probably fatigue!

As explained, the programmer proposes to configure a Frequency and Duration for opening the ball valve. When these 2 parameters are respected, the sphere of the programmer rotates 1/4 of a turn, always in the same direction. So by putting a Frequency = 1 hour and Duration = 1/2 hour, there will be a rotation of1/4 turn every half hour (opening every hour, then closing 30 minutes after); either 1 full turn of P1 in 2 hours, or in 24 hours 12 turns of P1.

I want to get a single full rotation of the P2 pulley in 24 hours, so I need an exact reduction with P1.

reduction tracker.jpg (21.64 KiB) Viewed 6023 times

On the programmer, the pulley P1 has a radius of R1, and the turntable P2 has a radius of R2. (On this tray will be placed a solar panel, a solar oven, a plant or any object requiring to remain facing the sun).

What is the exact ratio (R2 / R1) that will make a complete turn of the P2 stage in 24 hours.

A priori, R2 = R1 x 12, is that correct? ...

[izentrop]

Perimeter 1 must be 12 times smaller than that of the large pulley.

2 pi r1 X 12 = 2 pi r2
That's right

[Grelinette]

Perimeter 1 must be 12 times smaller than that of the large pulley.
2 pi r1 X 12 = 2 pi r2
That's right

Thank you izentrop for your confirmation ... (finally, after the fact, it seemed logical!)
I'm going to cut wooden discs and experience a tracker with this system. A priori, I think it is probably the simplest and most economical system to do if you don't want to get into electronic manipulation when you don't have the skills. It's just basic DIY.
The only downside would be that the precision in cutting the diameters of the pulleys generates an error that shifts the alignment a little bit in front of the sun every day. There are also rotating contacts to think about (for 1 PV panel), but that shouldn't be too difficult. Keep you up to date. (... and another new DIY on my workbench! )