Solar Energy Harvesting PCB — 97% Boost Efficiency

Overview

A microwatt-class solar harvesting front end with MPPT, sodium-ion charging and an ESP32 power interface — the same photovoltaic conversion discipline as spacecraft arrays, at the opposite end of the power scale.

Challenge

Design a microwatt-class energy harvesting board with 97% boost efficiency, MPPT for solar panel, sodium-ion battery charging, chemistry-flexible firmware, and 15nA shipping mode.

Our Approach

• e-peas AEM15820 energy-harvesting PMIC with 97% boost
• MPPT tuned to Voltaic 2.5W ETFE panel at 85% ratio
• Sodium-ion 18650 storage configured over I2C
• USB-C 5V fallback charging at 100mA CC/CV
• 15nA shipping mode for inventory storage

Technical Highlights

• 97% boost efficiency with e-peas AEM15820
• Chemistry-flexible: LiFePO4, Li-ion, LiPo swappable by firmware
• 15nA shipping mode for zero-drain inventory
• I2C telemetry and ESP32 driver library

Deliverables

• ✓Fabrication-ready PCB
• ✓Register configuration maps
• ✓ESP32 driver library and application sketch
• ✓Troubleshooting guide and BOM