A team from Pennsylvania State University has developed the next step toward solar-charged clothing by embedding solar cells inside flexible wires. Featuring the same basic arrangement as a standard solar panel, the wires are made up of a hollow, flexible fiber-optic thread with the inner and outer walls corresponding to the positive and negative layers of a solar cell. Thinner than a human hair and three feet long, the wires can be woven together to form a fabric—although currently that fabric is quite thin.