Typically, a wireless device has to be charged or have batteries replaced from time to time.
Logitech’s Wireless Solar Keyboard does this on its own since it is powered by any ambient light – not just the sun – feeding into a pair of solar strips.
A 2.4 GHz wireless connection is made with a USB receiver that also be used to connect a compatible wireless mouse.
Both PC and Mac computers (my tests were on a Mac) work with the keyboard, which can stay charged for up to three months in total darkness, according to Logitech. $60 at www.logitech.com.