Flexible solar panels aren't new, but they've proven to be markedly less efficient at converting light into energy than their bulkier, silicon-based counterparts. Using techniques inspired by OLED display manufacturing, a German startup called Heliatek has developed a new kind of solar panel that's both flexible and efficient, packing photovoltaic cells into a semi-transparent sheet.

The new solar panels operate at about 9.8% efficiency (converting 9.8% of light into energy), while earlier attempts hovered at around 4%. That's still a far cry from conventional silicon solar panel cells — which boast an efficiency of 15% or better and cost less to manufacture than Heliatek's cells. Nonetheless, Heliatek is working with manufacturers to integrate the technology into the facades of building and even tinted windows. The company is also working on improving efficiency, but its technology will face road blocks: in addition to the increased cost compared to silicon solar cells, funding for an unproven technology — no matter how promising — is hard to come by.