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Wireless devices continue to increase in popularity, and why not? They use fewer materials, so even non-RoHS (Restriction of Hazardous Substances) compliant devices are friendlier to the environment. And they are the ultimate solution to finding the right length of cable and avoiding tangling problems.

The difficulty is that they create a new consumable: batteries. When your battery dies, so does your mouse, keyboard, or other gadget. If you go with a rechargeable system, you’re back to being anchored by a cable, and you have to remember to plug it in to get the benefits of the charger.

Logitech's Solar-Powered Keyboard, the K750

Logitech’s new K750 solar keyboard addresses that problem with an elegant solution: solar cells that charge a battery backup. Using less than fourteen square inches of solar cells, they have created a wireless keyboard that can run on artificial light and run up to two months in the dark from the backup.

From the start, Logitech’s minimalist design catches the eye. Whether it’s the slender (one third of an inch thick) full-sized black and white keyboard, or the tiny (and I do mean tiny!) USB receiver, this system answers the question “why use more than you have to” with a resounding “we don’t!”

No PVC is used in the construction, and the box is fully recyclable. Warranty and warning information is printed on the inside of the box, so no additional paper is wasted. Just cut the box apart at the dotted line and save the language version you use. (This could use a bit of improvement, as this is probably not the most convenient shape for long-term storage, even though it eliminates the unnecessary use of additional paper.) As this keyboard uses their Unifying technology, you can run up to six compatible wireless devices off the one thumbnail-sized receiver.

Part of the fine print on the inside of the box is this warning: “Device Pairing Limitations. Some Unifying devices may be limited in the number of times they can be paired (connected) to a Unifying receiver. Although the number of pairings possible may vary, the minimum number of available pairings is 45.” If you plan to use your wireless devices on a lot of different computers, you might want to bring along your original USB receiver, just in case.

Unifying USB receiver.

My review copy didn’t have a manual, but you don’t really need a manual. You plug the receiver into your USB port, and the driver self-installs. (Windows XP, Vista, and Windows 7 only.) To use the keyboard, you pull the arrow tab out of the case, which activates the battery backup system. Peel off the protective film, switch it on (another sticker thoughtfully points out where the power switch is), and you’re running.

If you have questions, head on over to http://www.logitech.com/k750/support, where they have an FAQ list and software downloads. The current downloads are SetPoint and Solar App. Setpoint is highly recommended as it is how you customize your keyboard settings or allow another Unifying compatible device to pair with your receiver.

Out of the box, you can get a rough idea of the lighting by pressing a button located near the power switch. A green LED next to the smiley face momentarily lights if you have enough light. A red LED next to the frownie face flashes briefly if you have insufficient light.

The Solar App is an enhancement application designed to tell you how much light the keyboard is actually receiving, and also indicates how much reserve power is left in the battery. Once installed, the application is conveniently summoned by pressing the lighting button, and shows a real time graphic indication of how much light in the keyboard is receiving. The analog dial and digital readout are calibrated in lux units; a second display in the window shows how much power is left in the battery.

But you’re reading this to learn about the hardware, so let me get to it. The keyboard itself is a full-sized keyboard with all of the standard keys, and can either lay flat, or two small legs on the back can be deployed for a comfortable tilt. Despite its thinness, the board seems sturdy, but I wouldn’t recommend sitting on it. The usual F1 through F12 keys are there, and if you press the FN key at the same time, they have an added layer of functionality. Possibly as a power-saving feature, the Caps-lock and Num-lock keys do not have indicators to show when they’re engaged. (The SetPoint program allows you to briefly display changes in the lock keys’ status on-screen.)

The receiver uses 2.4 GHz to broadcast on, and 128 bit AES encryption (the current highest level) to protect your privacy, making this keyboard nearly as safe to use as a wired keyboard.

The thin keyboard lends itself well to storing it in narrow spaces, but you should consider leaving it out all the time: even with the power switch in the Off position, the solar cells continue to charge the battery backup. (An important point: when you finally change the batteries, use the ML2023 battery type, which they sell in their online store, not the nearly identical CR2023 battery. The CR2023 battery is NOT rechargeable. The ML2023 is.) Being a full-sized keyboard, it may not fit in your laptop’s carrying case.

If, like me, you’ve never added a second keyboard to your computer, you should know that adding this one does NOT override your original keyboard. So if you lay this on top of your laptop, you might get things that you did not type. For many people, this is going to be their only keyboard, not a secondary keyboard, so that won’t be a problem. Personally, I already like the feel of this one better than my laptop’s keyboard, so I will probably be adding their Unifying compatible wireless mouse: I don’t like to have to keep going back to the laptop’s touchpad.

Right now, it’s midnight, and the single light here in the kitchen only gives about 38 lux, which earns me a frownie face. But earlier in the day, the single bulb and the light streaming through the window gave me a respectable 87 lux. (It prefers lighting of about 100 lux, but stays reasonably content down to about 50 lux.) A properly lit office should have no trouble keeping the backup charged.

Pros: It’s a full-sized keyboard with all the standard keys. It has a nice, streamlined look and feel, very portable. No need to change batteries for years at a time, if you have adequate indoor lighting. It can charge the backup batteries even when turned off, when properly illuminated.

Compatible with their other Unifying wireless products, so you only need one USB port and one thumbnail-sized receiver (included) for up to six compatible devices. Good solid feel to the keyboard, and a pleasant feel to the keys themselves. Does what a keyboard ought to do, and has a theoretical maximum range of thirty feet, for those that like to use their home theater as their monitor.

The suggested price of $79.99 is comparable with Logitech’s other wireless keyboards.

Cons: I have an old keyboard by another manufacturer that gets something spilled on it at least once a year. I take it apart, clean and dry the plastic films that make up the switch matrix, and I’m back in business again. I wouldn’t want to try that experiment with this one, and I see no easy way to take it apart anyway.

I can find no mention of it being fully RoHS compliant at this time.

Logitech’s Nano receiver and the Unifying compatible receiver look exactly alike except for a small logo on the Unifying receiver (or some very tiny print on the Nano receiver). The Nano receiver cannot “see” the keyboard, so if you need a wireless mouse at the same time, make certain it’s Unify compatible or be prepared to give up another USB port.

According to the FAQs, it’s for modern versions of Windows only. Linux, Mac heads and anything older than XP need not apply.

The last con is a personal preference: there are no on-board indicators for the Caps lock and the Num lock keys. However, you can optionally use the SetPoint software to create momentary on-screen indicators.

I’d rate it 8.7 out of 10 and that’s being harsh.