New York Times: The aisles of a typical Walgreens drugstore are stacked with products promoting their green attributes, whether they are towels made from recycled paper or makeup brushes made from fast-growing grass. But increasingly, on the roof, a less visible green endeavor is under way, in the form of solar panels feeding power to the store. Walgreens, which has installed 134 solar systems across the country and has plans for many more, says its solar program stems from the brand’s connection to healthful…