Solar Charge Controller

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DIY Solar Charge Controller

Release status: experimental [box doku]

Description Trying to build and optimize a DIY solar charge controller
Author(s)  Severin

There are plenty of cheap solar charge controllers out there, but most of them are crap, or just don't really fit our use-cases. And the good ones are expensive. So let's try to DIY one.


  • PWM is ok, MPPT would be much better
  • Up to 32V battery voltage would be nice (24V Lead-Acid, 7S Lithium battery packs)
  • Free selection of cutoff voltages to accomodate different battery configuraitons (e.g. 3S/4S Lithium packs)
  • Data logging/telemetry

"Fancy" PWM controller

Starting point for the first shot at this is Open Green Energy's ARDUINO PWM SOLAR CHARGE CONTROLLER ( V 2.02) instructable. I started ordering some parts from AliExpress, and now "just" need to get the PCB manufactured and we should be good to go.

Group Buy

There were a few people who had shown interest in this project, so I ordered a bigger set of parts.

  • Nico
  • Uli
  • Sebastian (only if MPPT)


Taken from the instructable, needs some better specification for sure.

Part Amount Got it? Stock Source Notes
PCB V2.02 1 - JLCPCB
Arduino Nano 1 10 AliExpress
IRF4905 2 - Reichelt
MBR2045 1 - Reichelt
MP2307 1 - ? step-down should be fixed to 5V for arduino supply? or better adjustable ones?
DS18B20 1 - Reichelt? temp sensor for battery? maybe he meant this
ACS712 2 12 AliExpress
P6KE36CA 1 - Reichelt
2N3904 2 - Reichelt
Resistor 100k 2 - Reichelt
Resistors 20k 2 - Reichelt
Resistors 10k 2 - Reichelt
Resistors 1k 2 - Reichelt
Resistors 330ohm 7 - Reichelt
Ceramic Capacitors (0.1uF x 2) - Reichelt
20x4 LCD 1 6 AliExpress
LCD I2C Backplane 1 6 AliExpress
RGB LED 1 50 AliExpress
Bi-Color LED 1 - Reichelt
Jumper Wires - AliExpress? which length? what for?
Header Pins - Reichelt
Heat Sinks 3 20 AliExpress
Fuse Holder 1 10 AliExpress incl. cover
Fuses 1 - Reichelt No details as to what kind of fuse. Going with 4A fast blow for now
Push Button 1 - Reichelt
Screw terminals 1x6 pin 1 10 AliExpress
PCB Standoffs 4 - Reichelt
USB Socket 1 - Reichelt

Open Points

  • License is CC BY-NC-SA. If we want to build on top of this, we would need to clarify the NC part.
    • Email sent to OpenGreenEnergy to clarify this --Tiefpunkt (talk) 00:34, 8 November 2020 (CET)
  • USB port has no fuse, and also no resistors on the data pins. That might be a potential improvement.