Sustainable energy or as an energy input for other uses such as cooling equipment. In many climates, a solar heating system can provide a very high percentage (20 to 80%) of domestic hot water energy. Energy received from the sun by the earth is that of electromagnetic radiation. Light ranges of visible, infrared, ultraviolet, x-rays, and radio waves received by the earth through solar energy. The highest power of radiation comes from visible light. Solar power is complicated due to changes in seasons and from day to night. Cloud cover can also add to complications of solar energy, and not all radiation
Ultraviolet (Light My Way) naked eye and ultimately unknowable to the human intellect." Conversely, Steve Stockman, author of "Walk On: The Spiritual Journey Of U2", sees "Ultraviolet" as being about Bono's wife Ali Hewson, and "how when he feels like trash, she makes him clean," but says there is good reason to interpret the song as being just as much about God. The song's title supports this view: indigo and violet rarely appear in song lyrics as frequently as other colours, while ultraviolet represents an unseen wavelength beyond the visible spectrum. As such, the title evokes the image of black light or an invisible