Logitech calls its $79 Wireless Solar Keyboard K750 an innovation in typing technology, and after using our evaluation model for a week, we certainly agree. The dual solar panels mounted on top of the superthin keyboard require zero user effort to keep the device charged and ready to type, while the accompanying Solar App desktop software shows precisely how much battery life is left. We're very much in favor of the Logitech K750, especially when partnered with Logitech's convenient Unifying Receiver, which lets you connect multiple Logitech input devices to a single USB plug. In fact, we're giving it an Editors' Choice Award, and recommend it to anyone shopping for a new keyboard.
With its low-profile keycaps and a glossy black mirrored finish behind them, the K750 solar keyboard looks more like a disconnected laptop keyboard than its desktop counterparts. Unlike the mechanical keyboards currently popular in the peripheral market, this input device uses scissor switches underneath that register key presses with a lighter touch, and give the additional benefit of low noise. This type of keyswitch also allows Logitech to reduce the thickness of the keyboard chassis to just one-third of an inch.
The standout features on the K750 are obviously the dual solar panels that sit on either side of the logo branding on top of the keys. The panels power the integrated ML2032 lithium manganese button-cell rechargeable battery that then pushes power to the keyboard.
That's standard battery technology, but the solar panels can also draw perpetual power from artificial light sources--in other words, you don't have to raise the keyboard to the sun for it to work; the fluorescent bulbs above you will charge it just fine. Logitech claims that a single 2-hour charge will retain power for three months in total darkness, or more if you remember to flip the on/off switch when you step away.
Finally, on the small chance that the battery fails, you can replace it with a standard ML2032 battery, available from Logitech's parts store.
Just above the 10-key pad, you'll find a small "check light" key that indicates the remaining battery life using basic icons that everyone should understand: a green smiley-face lights up if you're powered up, and a red frown lets you know your light source is currently drawing less than 50 lux.