Project brief
A high-performance MPPT solar charge controller for off-grid solar systems supporting 60A output current and 150V PV input. GaN FET switching at 500kHz reduces filter size and improves efficiency to 97.5% (CEC weighted). Supports lithium-ion, LiFePO4, lead-acid, and gel battery chemistries with programmable charge profiles, and provides BLE 5.0 monitoring via a mobile app.
The design narrative combines power conversion and charge-management controls. It introduces no additional efficiency or energy-yield results.
The engineering challenge
Coordinate solar harvesting, battery charge profiles, and thermal protection across changing source conditions.
Engineering approach
- Use source measurements to drive the stated tracking controller.
- Apply chemistry-specific charging behavior through programmable profiles.
- Integrate load switching, protection states, and mobile monitoring.
Features & capabilities
- Input: 18–150V PV, output 12/24/48V (auto-detect), 60A maximum
- Perturb & Observe MPPT with 99.2% tracking efficiency
- 97.5% peak conversion efficiency using GaN FETs (GS66508T) at 500kHz
- Multi-chemistry: Li-ion, LiFePO4, lead-acid gel/AGM, custom profile
- BLE 5.0 mobile app: real-time monitoring, production/consumption history
- Protections: overcharge, over-discharge, over-temperature, reverse polarity
- Load output: 30A switched output with LVD (low voltage disconnect)
- Fan control: PWM temperature-proportional cooling with 40°C turn-on
Software & engineering tools
STM32G474, GaN FETs, custom toroidal inductor, 4-layer PCB, Altium Designer, BLE nRF52832 module