Logitech Solar K750[1] has served me well. 3+ years now and still going strong.

The model that I have can be easily updated to use regular batteries, once your solar interface goes bust. [2]

[1] https://www.logitech.com/en-us/product/wireless-solar-keyboa... [2] https://www.ifixit.com/Guide/Logitech+K750+Keyboard+Battery+...