“‘Solar ink’ … is designed to capture sunlight and turn it into electricity. A fine layer of this ink is then deposited onto a material, such as plastic. … Silicon is falling in price, but think about how cheap plastic is.” (http://www.theguardian.com/world/2014/sep/10/solar-energy-cells-you-can-print-out-catching-commercial-eye-says-csiro)
Cheap? Plastic? Haven’t you heard that cheesy old record, ‘Please renew me’ by Engelbert Solarink?