In midsummer, near noon on a clear day, full sunlight approaches light intensity of 1000 Wm-2. Since about 45% of sunlight is in the 400nm to 700 nm range used for photosynthesis, plants can only use about 450 Wm-2 or about 2000 micromol m-2 s-1. Similar or higher intensities can be achieved using artificial light sources like HPS,MH, LED grow lights, but this requires considerable costs for both power and lamps.