Since we're on the topic of the Solar App let's take a closer look. The app is started by pressing the dedicated solar button (top right, above the number pad). It displays the dynamic light levels (measured in lux) that the keyboard is receiving. Below this is the battery life (which can be toggled to show the battery life over one, three or 12 months) and a report on the battery status. It is simple and nicely designed.
So what do we learn about Logitech's ambitious battery claims. Quite frankly for a product designed to last months at a time without any light whatsoever it is hard to gauge in the short term. What we can tell you is in a week's worth of journalist-quantity typing (going on for 8,000 words) the battery has never dropped below 100 per cent. The keyboard is positioned in a room where there is an external light source, but it receives little direct sunlight. It seems there is every chance the K750 will never need mains power.
The freedom this creates is fantastic since the keyboard is instantly tethered to whatever the tiny USB wireless receiver is plugged into. This makes it great for multimedia setups and is particularly useful when you grow weary of typing on a laptop, especially smaller netbooks. The receiver itself also has a nice touch. Logitech dubs it the 'Unifying receiver' and that is because it will happily pair with multiple Logitech wireless peripherals. This frees up USB ports, something that is especially handy for laptops.
As for range, the receiver uses 2.4GHz wireless which means you'll get obstruction free range of around 30 feet and even get away with a single wall in the way. Quite how you're meant to see what you're typing in this scenario is another matter. There is virtually no input lag and I found it flawless for gaming (at least to my gaming standards).
So all this and no talk of how good this fancy keyboard is at actually being a keyboard. Happily we've left the best until last. With the growing dominance of laptops, Logitech has consciously gone for a chiclet design which makes switching between a modern laptop and this keyboard a breeze. As the marketing brags: "it almost feels like typing on your laptop, but more comfortable" and that hits the nail on the head.