What we have here is an expandable strip that opens up to get recharged in the sun. It rounds up to the shape of AA, AAA and C-sized battery. Basically you can customize the size depending on what you need and recharge it via the solar cells.
Read more at http://www.yankodesign.com/2012/10/25/solar-and-customized-cell/#cqIod6KYbFXCkfRs.99