The science behind solar（太阳的）energy is not new.But Sheridan Community Schools is the first school district in Indiana to be completely solar-powered. The district finished installing solar panels（太阳能板）for all three of its schools in 2016. Some of the panels can turn to follow the sun across the sky. Sheridan's solar push is part of a trend. In 2008, fewer than 1,000 schools used solar power. By 2014, there were 3,727 schools with solar panels in the US. This data comes from a report by the Solar Foundation,an organization that promotes the use of solar power. Roxie Brown, a program director there,says that the number of schools with solar panels has continued to rise since 2014. (79) Solar power has some obvious advantages over other energy sources. Sunlight is a renewable（可再生的）resource，which means it won't run out. Solar panels don't harm the environment. Also, sunlight is free. So by using solar power,schools can save money on energy costs over time. But switching to solar power isn't always easy. Solar panels can be expensive to install. Sheridan Community Schools had to borrow money to pay for its solar transition. (80) The panels also take up space.But for many schools,going solar is worth it. The use of solar energy can also help students learn about electricity and environmental issues. Teachers at schools that use solar power often incorporate it into their science lessons. The kids talk about it in the classroom. Then they can look at it in action. According to Brown. the educational impact of solar panels is "the most compelling reason"for schools to install them. Brown hopes the panels will give Sheridan students a global perspective.“The world is bigger than the boundaries of their school district," he says.“They're doing things to help the world as a whole.”