The sun is the source of energy for all living things on earth are no exception to plants. For humans, the sun is useful for drying clothes and even food that needs the drying process as well as energy sources which will then be converted into electrical energy as well as the many benefits of solar to farmers.
As for animals, the sun is useful to warm the body, helps digestion of food and also the absorption of calcium in reptiles. Without the sun, plants can not grow fertile so the sun is needed to nourish the growth process, and many more benefits from the sun.