Issue Using ACS712 Current Sensor and Voltage Sensor Simultaneously with Solar Panel

Using Arduino Sensors
1

Hi everyone,
I'm working on a project where I’m trying to measure both current and voltage of a solar panel simultaneously using an Arduino. Here's my setup:

  • Current Sensor: ACS712 20A, connected in series with the solar panel to measure short circuit current.
  • Voltage Sensor: Modified voltage divider (increased resistance to measure up to 50V), connected in parallel with the solar panel to measure open circuit voltage.
  • Solar Panel: Measuring the current and voltage directly without a load.

The Problem:

The current sensor works fine when it’s connected alone, but when I try to connect the ground of the voltage sensor (the negative side of the voltage divider, the grey wire in the picture) to the *negative terminal of the solar panel, the current sensor stops working, and the voltage sensor starts giving voltage readings and when the grey wire is removed the current sensor starts giving values again .

I’ve tried connecting everything to the same ground (solar panel negative, Arduino ground, current sensor ground, and voltage sensor ground), but the current sensor seems to stop measuring whenever the voltage sensor is connected.

Questions:

  1. Why is the ACS712 current sensor stopping when I connect the voltage sensor's ground to the solar panel ground?
  2. Is there a better way to ground both sensors so that they work simultaneously without interference?

I’ve attached a picture of my setup and wiring.

Any help would be greatly appreciated! Thanks in advance.

solar panel current and voltage diagram
solar panel current and voltage diagram2826×1643 159 KB

2

Do you have a load? Like R in this schematic?

image
image1608×1002 52 KB

The current sensor should be in series with the voltage source and the load, while the voltage sensor should be in parallel with the load.

You can't measure open circuit voltage and short circuit current simultaneously. You can simultaneously measure current through a load and voltage across a load.

3

this is how i measure them using a DMM, can i use a resistor as a load?

4

no load, just measuring open circuit voltage and short circuit current

5

Measuring short circuit current like that can be dangerous with large currents. A car battery could provide 300A+ Most DMMs specify a limit of 10-20A before they are damaged.

What is your open circuit voltage and your short circuit current?

Yes, but it should have enough wattage to cover the current flowing through its resistance. Do you know Ohms law?

6

my Voc is around 43V and the Isc is around 9.7 AMPs
when i measure each one alone i get these readings, but i need to measure them together to get the POWER and make the IV curve

7

The voltage measurement will have to be across the MPPT primary, that is the load for the panels.

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