Below is a Mermaid code block representing a high-level block diagram for your power system:
Diagram
This diagram shows:
Inputs: Solar Panel, USB, and LiIon Battery.
Power Management: Schottky diodes provide reverse current protection; battery charging via the MCP73831; and automatic selection via the power select circuit.
Voltage Regulation: The battery is boosted to a regulated 5V by the MT3608, which then feeds two buck converters that generate 3.3V and 1.8V.
Indicators: LED indicators display charging and power status.
You can use this block diagram as a reference to develop your detailed schematic within your Flux project.