It is fully autonomous and it can run on a full 18650 battery for about 5 days if there is no sun, otherwise it can run indefinitely thanks to the 1W solar panel.
The KA75330 voltage detector will cut power to everything if the battery voltage is below 3.3V. This allows it to recover even after being completely discharged and when the sun is slowly rising (thus avoiding ESP brownouts)
During sleep it uses less tham 1mA, however the sensors use 100mA during the heating period so some values are updated less often.
Sensors and modules:
MICS-6814 - for measuring gas concentrations
CCS-811 - for measuring CO2
ADS-1115 - for precisely measuring the (analog) output of the MICS sensor
TP4056 - Battery charging module
ESP32 C3 Mini (Lolin)
Thermistor - for measuring the battery temp. V3 of this project will stop charging when temps are not safe but for this one I am just gathering data
Case: slightly modified version of https://www.thingiverse.com/thing:2282869
PCB: Custom design by me using EasyEDA
All data is sent to home assistant through the internet through HTTP POST so the weather station need to be in range of WIFI.