Most people have seen solar tubes on TV. They enjoyed a popularity surge in the late eighties and early nineties. Solar tubes offer an inexpensive alternative to sky lights. In some cases, they can even offer more light, do to the technology that they use. In essence, the reflective material on the inside of the tube intensifies the light as it goes down the to a single lens surface protruding through the ceiling, and lighting up the room. Where a skylight is going to require a major remodel of your ceiling and a precision 2×4 square cut from your roofing a solar tube requires only a small hole between 18″ and 24″ inches and a similar hole inside in the ceiling.Get more information here. http://blog.smarthome.com/2012/08/12/led-light-fixture-uses-renewable-energy-dims-and-brightens-with-the-sun/
Where a skylight requires that the roof hole and the ceiling hole be exactly lined up. The solar tube allows you to put the roof hole and the ceiling hole offset of each other. This does not affect the functionality of the light. This allows you to move your light so as not to cut your trusses up when going through the roof cavity. It also gives you more options with centering your interior lens in the room so that it has maximum light benefit and maximum appeal.