If you have been researching LED grow lights for your plant growth facility, you have likely been ending up with a variety of information that lighting manufacturers use to market their products: watts, lumens, LUX, PAR, PPF, PPFD. In our opinion, you want to buy a lighting system that delivers the required amount of light to your plants. In order to explain the correct method for evaluating a horticulture lighting system, it may be a good start to focus upon what you need to avoid.
First, the watt of the LED’s is not relevant. The wattage of the LED use in light does not tell you anything meaningful about the lighting system’s performance since LED and fixture efficiency varies widely. Remember, the LED wattage is a system input, and growers care about the system output–PAR Output. Hence, the lighting system using a certain wattage needs to be compared to the watt it is consuming to produce PAR.
Second, do not look only at one PPFD measure. Unless you are growing a small plant directly under your light, a single PPFD measurement does not tell you much. By clustering the LEDs closely together and using narrow beam optics, it is very easy for a manufacturer to show an extremely high PAR measurement directly under the fixture. However, unless you are only growing one plant in this exact location, you need to know how much PAR is being distributed across the entire canopy.