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Direct Solar Lighting

The most efficient indoor lighting!
NOW EVEN BETTER !!!! (LINK)
How it works:
Normal skylights let in the sun's rays but do not have a way to amplify or shade the amount of light (and heat) entering the fixture. Using built-in reflective surfaces and mirrors guided by an infrared solar tracking device, these lights significantly increase indoor light levels during early morning and late afternoon hours. The mirrors can be programed to reflect "high noon" heat during the hotter months...keeping light levels up but reducing the cost of air conditioning.

On a related topic: "Why are so many modern buildings designed so the windows won't open?"
More on sun tracking skylights!