[jaegerpicker]

Wrong question to ask, PPFD's is the correct measure. It's not a direct energy comparison. Photosynthesis is a chemical reaction of Chlorophyll reacting to certain but not all light wavelength's (Red and Blue being the major ones) plus the distance from the light source. The amount of watts the the sun generates is NOT what grows plants. LED's can produce the same light wavelength's but much closer and with no obstructions. The question isn't about LED's power generation, it's how much power does it take for an LED to cover an area. Obviously a LED can't compare to pure Solar efficiency on a watt by watt basis but it doesn't need to.