homeassistant

As someone who owns these, I still have to charge them from time to time. My windows have some built in UV blocking and my home has an overhang. This won't matter for OP but the cords are short enough you have to put the solar panel at the top of the window if you plan to open it at all so part of the day the overhang blocks the sun. Then it also matters where the window itself is positioned to get sun. I use a backup battery you would use to charge a cell phone and just set it on the trim over the window and then come back for it in a few days when I finally remember. But my windows aren't 20ft in the air. It varies from window to window but it's usually several months between charges as the solar panels do charge enough during parts of the year.

Above is a year of battery data from my worst window and one of my better ones. It's heavily dependent on how close to a south facing wall the windows are. And of course, how your open close routines are setup.

Edit: These windows are in the same room on the same wall. The bad one is close to the northern corner of the house and the good one is close to the southern corner of the house. They are in my living room with our TV and open and close regularly as they shut when the TV is in use and open when it's not.