Deutsche Welle: “Cooled using sunlight” – it may not be that unusual to find that label on food packaging in the future. Researchers are hoping to use the sun’s rays to keep fruits, vegetables and other perishable goods fresh for longer periods, particularly in developing nations where refrigerators are often a luxury and only densely populated regions are connected to the electricity grid. Poorer southern nations also need technologies to cool medicines and vaccines to avoid spoilage, especially in …