In a continuous deep-sleep scenario, the system can operate for several days without sunlight.

In this first experiment, a simplified firmware was used to keep the system in permanent deep sleep. The fully charged supercapacitors powered the ESP32-C3 through a DC/DC converter, operating down to an input voltage of approximately 1.5 V. Below this threshold, the converter disables output regulation and the ESP32-C3 can no longer maintain a stable supply.

Under these conditions, total runtime reached nearly 6 days.

This test demonstrates the feasibility of multi-day autonomous operation using only harvested solar energy stored in supercapacitors, without any battery buffer.

For data logging, a custom-built hardware device was used to measure the supercapacitor voltage. The data samples were stored and visualized using the Home Assistant environment.