Solar energy originates from the sun and represents the entire electromagnetic spectrum that reaches Earth. It has the advantages of being pollution-free and sustainable, with the energy from 30 days of sunshine having the equivalent energy of all fossil fuels used and unused on Earth. Challenges include its diffuse and intermittent nature. Various technologies have been developed to collect, convert, and store solar energy for heating water and living spaces as well as generating electricity through photovoltaics and concentrating solar power towers and dishes. While solar technologies are improving, their higher initial costs compared to fossil fuels have limited widespread adoption.