Good day


  1. Solar panel (with a maximum output current of 2100 mA and an output power of 25 W; Output voltage - 5 V). These parameters are stated on the seller’s website and may differ from reality.
  2. development board NodeMCU v2
  3. Raspberry Pi 3 Model B +
  4. Arduino Uno and a bunch of loose powder (resistors, conders, transistors, diodes).

What I want to do:

Using a small home-made arduino-based multimeter, take readings (voltage, current) from the solar panel throughout the daylight hours. Store the readings in the logs and transmit them to the server (as the transmitter, the Node MCU board, and in the role of the server, the raspberry), where the data will be plotted.

A huge request to you - a novice, that is, me, poke his nose into any subject literature on this issue. How to correctly implement all this.

If this algorithm is technically impossible to implement, are there any such ready-made tools?

1 Answer 1


2.1 A * 5 V = 10.5 W

And the arduino can measure both voltage and current, if you implement it well. Think of ohm's law.

Arduino has inbuilt 10-bit ADC which can measure voltage from 0-5 V. If the current to be measured is passing through a known resistor R, hook the nodes of the resistor to two analog pins on the arduino. Use analogread() function to find the two node voltages. Calculate the difference to get the voltage drop across the resistor. Then I = V/R. Calculate it and print the value on the LCD.

Source of the block above

There are some other ways, but I think this will do.

Or you could use the sensor hat the other answer proposes, that is even easier.

  • This answer a question to Arduino but not to Raspberry Pi.
    – Ingo
    Commented Nov 6, 2019 at 10:06
  • Isn't the hat i2c? And sorry, I thought I was on electronics. I will flag my answer.
    – Dr_Bunsen
    Commented Nov 6, 2019 at 14:55

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