Energy consumption in the world is increasing more and more due to the huge energy request coming from emerging countries such as China, India, etc. To face the challenge of sustainability, a solution may be the use of solar energy, since it is the most abundant renewable energy source on Earth. The electromagnetic energy coming from the Sun can be converted into usable energy (electricity) by solar cells, whose conversion efficiency is continuously increasing due to scientific and technological progress. The proposed activity is thought to be carried out with secondary as well as high school students to allow teachers to discuss sustainability issues, and to provide students with an introductory view into modern physics aspects (quantization of energy levels), quantum mechanics (semiconductor band energies), and radiation-matter interaction. Furthermore, cutting-edge research in physics can reach school students, increasing their interest in scientific studies.