Excellent point! Also....the quality (longevity) should be factored in, also. My mars light is losing a diode approximately every two months.....Remember to factor in that the savings go a little beyond just the watts at the wall of the lights themselves. Since they are higher efficiency and using less watts, they are also producing less heat. So less ventilation needed, less A/C to counter the heat generated by the lights, etc..etc.... :smoking: