In March 2015 Bookeen announced it is developing a solar-powered e-reader cover in collaboration with Sun Partner. The Solar Leaf Cover is now available exclusively for Bookeen's Cybook Ocean, for $67.
The cover has a 19 inch2 (125 cm2) patterned solar panel that can charge the e-reader. A one-hour exposure to a brightness of 25,000 lux is enough to charge the reader for about 30 minutes of reading.
Bookeen will also offer a similar cover for the company's 8" Noimbook XL reader.