I’ve used the Logitech Wireless Solar Keyboard for two months and am impressed. Wireless computer peripherals are a great productivity tool for enabling freedom of movement, and because it uses solar panels it is only 1/3″ thick (no thick battery compartment), and no need to worry about charging/replacing batteries. At the same time it feels more durable than any keyboard I’ve used before. It replaced my prior favorite, the Microsoft Natural Ergonomic 7000 wireless.
The K750 has instant responsiveness compared to the slight delay in response when using the Microsoft after a period of inactivity. It feels built to last, not made of cheapo injected plastic, and more along the lines of an Apple product. The nano-sized USB Unifying receiver can connect multiple Logitech peripherals, which is handy for me since I also have a Unifying-compatible Logitech mouse.
As far as the solar charge is concerned, I use it throughout the day in a room that has a window but not a lot of direct sunlight. I also use it for several hours at night with no apparent loss of functionality. It actually has a little button to the left of the on/off switch that lights an LED beside either a smiley face or unhappy face to indicate whether it has sufficient/insufficient light.
[Steve burned the candle at both ends to test whether or not there was a loss of power after extended use without light. He found no loss of functionality even after working in the dark for 8-hours.--OH]