Measure voltage from solar panel

Other Hardware General Electronics
1

Hy everyone!

I'm working on a homeproject where I want to measure the voltage of a solar panel with my arduino uno.
So, I've done the basic tutorial with the arduino as the power source and a potenitiometer as a resistor. It worked like charm!
But then I realized, that my solar panel Open Circuit voltage is 22.50V (It's an 80W panel with 22.50V Open cicuit voltage and 4.69A Short circuit current).
I'm a total noob when it comes to electric circuits and it's accessories so I'd like to ask for your help.
So the question is, what resistors and other stuff do I need to measure the voltage of the panel and keeping my arduino safe at the same time?
Can I still use my 100kohm potentiometer or do I need something bigger?

2

You need to use a voltage divider. I suggest a 10K resistor from the analog input pin to ground, and a 47K resistor from the pin to the positive side of the solar panels. That will give you (10/(10+47)) * 22.5 = 3.95V at the pin when the panels are producing 22.5V.

3

Thx for the quick answear!
Do I need to bother with the negative side of the panel?

4

The negative side of the panel needs to be connected to Arduino ground. Is that permissible? What will the solar panel be powering?

5

Well... it won't power anything.
I just want to measure it's produced voltage. Do I need a power consumer in that case too?

6

Mark5217:
Well... it won't power anything.
I just want to measure it's produced voltage. Do I need a power consumer in that case too?

No, I just wanted to know if there was any reason you couldn't connect the negative side of the panel to ground.

7

Do I need a power consumer

What does measuring the Open Circuit Voltage tell you ?
Depending on the sunshine intensity you will "always" measure about 20V, but can draw between 0 and 4A ( 80W = 4A*20V, a bit simplified)

8

I knew that that W=V*A . So I know it will always show about 20 V.
I don't really know what does it tell you.