ZephyrOS: https://github.com/zephyrproject-rtos/zephyr
Would there be value in modeling this system with TLA+?
Why build another open product?
There are a few GitHub topics for solar electricity:
solar: https://github.com/topics/solar
photovoltaic: https://github.com/topics/photovoltaic
pv: https://github.com/topics/pv
battery-management: https://github.com/topics/battery-management
ups-management: https://github.com/topics/ups-management
inverter: https://github.com/topics/inverter
Photovoltaic system: https://en.wikipedia.org/wiki/Photovoltaic_system