Mppt Solar Charge Controller
An MPPT solar charge controller for a caravan. Hardware, Firmware, Webapp for visualization
Hardware main parts:
- Schematic PDF download
- No PCB design so far, just a working prototype on breadboard
- STM32 MCU (bluepill STM32F103)
- SZBK07 DCDC module (LM25116 DCDC driver chip and other electroics removed just power electronic parts used)
- 250W solar panel 36V nominal voltage
- Split charge relay for charging from engine, when driving (separate from this circuit)
- 55Ah and 110Ah 12V leisure batteries in parallel
- 3x ACS712 current sensors
- ADS1115 ADC for current measurement
- FAN for cooling power electronics
- Bluetooth UART module for communnication
Firmware:
- Written in C
- STCubeMX generated base project + user code
- 50Hz controlling loop
- DCDC half bridge controlling via complementary PWM signals
- MPPT tracking, float charging
- simple ASCII UART protocol for communication
- active PWM fan control when power is high
Webapp:
- Python3 based
- Flexx UI
- For visualization and active control of the firmware
- Connection via bluetooth
- Could be running on a raspberry PI
Android app
- There is an initial release of the android app, it is working but not perfect