ads do portable generators power portable signs warning motorists of lane closures or other important news. Solar cells have replaced them. As the increasing demand for electricity starts to clog the world’s power lines, like traffic jams on our freeways, solar cells strategically built on or into homes and buildings can provide the much needed electricity without further burdening the old electrical routes. Or at times, like on a hot August afternoon, when the electrical highways have emptied, mini-electrical plants consisting of solar modules can refill transmission lines to prevent brownouts and blackouts. The skyrocketing price of oil and natural gas and their dwindling supplies as world demand continues to grow will force the world to use more and more electricity generated by the sun. The change from fossil fuels to solar cells will also help clean up our polluted skies and keep a lid on global warming. As Science magazine wrote more than twenty years ago, “If there is a dream solar technology, it is solar cells, a space-age electronic marvel at once the most sophisticated solar technology and the simplest, most environmentally benign source of electricity yet conceived.