@4764c84a Try the Logitech Solar Keyboard K760. I've had one for more than 10 years now. Charges directly through solar or ambient light. I just keep it out in the light and it's always charged.

https://www.amazon.com/Logitech-Wireless-Solar-Kebyoard-iPhone/dp/B007VL8Y2C 

 @7b4cefd3 I have one somewhere. lol. I loved mine. I might just get a new one as there is a nasty cracking sound when I type on mine lol!