# DC motor driving solar panel

Hello,

I'm currently making a portable solar panel for my senior project. The main part of this project is that the solar panel will spin until it hits a certain angle and then delay for an hour, then it will repeat until the end of the day (12 hours). I had a bit of code written up for a stepper motor, but my partner bought a 12V DC motor instead. It's too late in the semester to try and get it replaced.

I've discussed this problem with one of my teachers, and he recommended using a potentiometer to delay the motor once it hits a certain resistance/analog value.

I'm a bit confused as how to do this, and any push in the right direction would be appreciated.

Thanks.

trussell97:
Hello,

I'm currently making a portable solar panel for my senior project. The main part of this project is that the solar panel will spin until it hits a certain angle and then delay for an hour, then it will repeat until the end of the day (12 hours). I had a bit of code written up for a stepper motor, but my partner bought a 12V DC motor instead. It's too late in the semester to try and get it replaced.

I've discussed this problem with one of my teachers, and he recommended using a potentiometer to delay the motor once it hits a certain resistance/analog value.

I'm a bit confused as how to do this, and any push in the right direction would be appreciated.

Thanks.

We can tell how confused you are. The solar panel will spin? Do you mean the panel rotates around a vertical axis?

The certain angle is determined how?

How fast does the panel rotate? I guess you could move the motor for some certain time and hope? How exactly do you go about powering the motor?

Is the potentiometer attached somewhere or is it manually rotated?

Do you intend this machine to operate for more than the first day?

Paul

Details on the motor, potentiometer, and power.

It sounds like he is recommending making a linkage to position the potentiometer so that it varies with the position of the solar panel. This will then act as a feedback to the program that drives the positioning motor. Read up on how servos work to understand the principle of using positional feedback in the control process.

You should discuss how you intend the mechanical linkage to work, if you want more specific help. If I assume that you are using a threaded rod or similar lead-screw, then another option could be to use a simple shaft encoder to measure the actual shaft movement as you drive it. For the type of positioning needed, just counting revolutions would give you enough position resolution and an IR reflectance sensor and a piece of tape on the lead screw would give you a pulse train to do the counting.

Paul_KD7HB:
We can tell how confused you are. The solar panel will spin? Do you mean the panel rotates around a vertical axis?

The certain angle is determined how?

How fast does the panel rotate? I guess you could move the motor for some certain time and hope? How exactly do you go about powering the motor?

Is the potentiometer attached somewhere or is it manually rotated?

Do you intend this machine to operate for more than the first day?

Paul

Details on the motor, potentiometer, and power.

Sorry, guess i wasn't specific enough
The solar panel is attatched to an axis which is spun by the motor.

The angle starts at 45 degrees at the start of the program and ends at 135 degrees over 12 hours, which means it would have to spin at 7.5 degrees per hour. (the idea was for it to absorb as much power from the sun as possible) the 7.5 degrees is equal to about 8300 ohms and 0.41 V based on the pontentiometer which ranges from 1.5ohm to 100k ohm, and the analog value from 0-5V

the motor is rated at 60rpm, but I don't want it to spin that fast since it will have to delay itself after it hits a delay.

the motor is powered by 1 of 4 car batteries connected in parallel, which are filled by the power absorbed by the sun.

We want it to be able to run 12 hours everyday, or as needed.

Hope that answers the questions, thanks!

Thank you! That does help a bit.

I am guessing that you have a proper charge controller between the solar panel and the storage batteries. If not, then your project will slowly die. The controller will stop the battery discharge during the night.

You explained what you want to happen the first day. What do you want to happen on day 2?

Please compute the number of power pulses to the motor to make it move a small distance, so the sum of the pulses will equal your 7.5 degrees in one hour. That is the only way I see to reduce the speed of rotation of your solar panel. The difference between periodic movement and continuous movement will not matter to the solar panel. You can program your Arduino to provide a power pulse to a MOSFET that will provide momentary power to the motor.

Paul