As a planet, we're using ever more energy. Meanwhile the economic and environmental cost of fossil fuels is becoming increasingly worrying. The hunt is on for reliable and affordable eco-friendly alternatives. Solar power will be a key part of that future green energy mix. Organic photovoltaics (OPVs) could be produced in high-throughput, roll-to-roll processes – cutting the cost of solar panels. What's more, as they are light, flexible and offer complete freedom of shape, OPVs could be integrated directly into building materials and electronic systems, making "solar" power attractive both indoors and out.