There’s no question that eBook readers are here to stay. The mighty Amazon alone is selling around 5 million of them a year, and they’ve publicly stated that ebooks are now the biggest selling book format jumping off their virtual shelves. It’s not hard to see why. The convenience of carrying around a literal library of titles wherever you travel is really compelling, and despite what purists may say, reading on a screen can be every bit as enjoyable as paper.

One problem though, is the fact that you’re still limited by the battery on your device, which is why companies are trying to introduce products to make this issue go away. The Solar Focus Cover for Kindle 4 is one such product, offering an eco friendly solar powered case which includes a light to let you read at night, in dark areas and other inhospitable places and still keep your battery alive.

The cover can extend the battery life of your Kindle by three times, and features USB charging as well, in case the sun goes in for a long time or you spend a lot of time underground. One hour’s solar charge promises up to 3 days reading time, which should be enough for most people, even coal miners. The device is priced at $79.99.