So, for 800 lumens, the calculation would be 800 lumens / 80 = 10 watts. By contrast, a traditional incandescent bulb would require approximately 53 watts to become as luminous as a. These bulbs produce the same levels of brightness (lumens) as older incandescent and halogen bulbs, but with a fraction of the power (watts). As an example, to produce 480-720 lumens of light might require 40W of power for an incandescent bulb, but only 6-7W for an energy-efficient LED bulb. If. Lumens in Solar Lighting: How Brightness Really Works (Watt vs Lumen Explained) Lumens tell you how bright a solar light will actually be. If you want a solar light that truly lights up your garden, street, or security area, you must look at the lumens—not watts. It offers the same brightness with the added benefit of.