Looking at how easy it is to power a small basic "weather station" (hama ews-151, a thermistor with a 433MHz transmitter really) with a small solar panel from aliexpress.
Out of the box the transmitter is powered with 2 AAA batteries and would work more than 4 months on these.
The panel is a small 4x4cm thing:
https://www.aliexpress.com/item/32814927225.html?spm=a2g0s.9042311.0.0.468d4c4dT9MHz0 (I can go with a slightly bigger one if necessary).
Assuming the panel would produce 1/10 of the specified power (140mW/10) on an overcast days it should still be enough to power the sensor/transmitter.
The question is how difficult it is to hook this up to a small 100mAh 3.7V li-po battery for energy storage and power the transmitter from this setup.
My understanding is that the panel's voltage would go down to 0.2V on overcast days (from its max of 2V) so the boost converter/charger should allow input voltages down to 0.2V.
Then I'll need to charge the battery and power the device at the same time during daytime.
I'm wondering if there's a standard chip/module for this sort of job.