Logitech has achieved what even the Swiss company thought was impossible a couple of years ago, a completely solar powered wireless keyboard, one that can store enough energy to use up to a staggering 4 months in total darkness.

Featuring two solar panels along the top, the K750 Logitech Wireless Solar Keyboard can be charged from either the Sun or an indoor lamp and has a lifetime of around 15 years before any degradation in performance. In fact, it is more likely that the keys and moving parts will wear out before the internal cell or panels do.

Pocket-lint visited Logitech in its new Daniel Borel Innovation Center in Lausanne, Switzerland to try out the new keyboard, and chat to the company's vice president Product Marketing, Denis Pavillard. During which time, he revealed to us that the K750 is a mere 7mm thick - with the boast that it's the slimmest keyboard in the world - and is five times more energy efficient than any other keyboard Logitech has made.

The solar panels haven't come about at the expense of design and comfort though, as it features the company's proprietary cushion design; contoured keys that allow your fingers to sit naturally in them.

But it is a combination of internal technologies that really got the Logitech designers working overtime. The K750 features low power integrated circuits, a power optimised wireless link (Unify - the manufacturer's 2.4GHz wireless system that can handle up to six devices at once), and an ultra low leakage buffer battery.

It is these elements, together with the indoor-centric silicon solar cells, that make the product work its magic: "This is really what enables the story to work", said Denis. "You don't always have light. You cannot have a keyboard that stops working".

"So we built a buffer of energy within the product, and whenever you're not typing, it fills up. If you leave it in the dark, it will work for three to four months".

Logitech has also created a free desktop app for Windows that can accurately tell you how much energy is currently stored in the K750, and what the current light level is for charging purposes. That's available from the company's website, regardless of whether you have the keyboard or not... Although we're not sure why you'd want it in that instance.

The one thing that won't be available any time soon, however, is a solar powered mouse to go with it: "There is no plan to create a mouse", Denis told us. "At some point it will happen, but with a mouse, there is less real estate. And you put your hand on it".

"This is a very different challenge, and we will see what happens there in a couple of years".

At present the K750 Logitech Wireless Solar Keyboard is PC only. It will work on a Mac, and would look lovely (as our pictures alongside Apple's Bluetooth keyboard show), but the key configuration is wrong. That's not to say the Swiss manufacturer won't bring out a compatible one in the future though.

For now, this version will cost £69.99 in the UK, 79 euros elsewhere in Europe, and will exclusively be available (for the time being) on Logitech's website from December, just in time for Christmas. The K750 will make it onto the high street in early 2011.

And, as a side benefit for those who are looking at it as an ecologically sound option, all of the packaging is recyclable, and has been trimmed down so there is very little waste.

Now that's thinking of the polar bears.

What do you think? Will you consider a completely solar powered keyboard? Would you like to see other solar powered devices? Let us know in the comments below...