What are the best LED grow lights? - Actual LED output wattage & coolding system (2/5)
ACTUAL LED OUTPUT WATTAGE
Comparing LED grow light power
When comparing LED lights to HID lighting (HPS/MH), use the actual LED output wattage. To get an equal amount of photosynthetic active radiation from LEDs as you would HID lighting, use about 50-75% less wattage than a HID setup. For example, to get 1000 watts of actual LED power you could use 2 LED panels that draw 500 watts of power in place of a 1500-2000 watt HID system. These numbers represent a wide range, and the actual power will differ depending on the brand, diodes, lenses, etc. Most importantly, do not use the advertised wattage of, say, a panel that has 350 x 3 watt chips. This does not equal 1050 watts of actual power. It is closer to 500-600 watts of actual LED power. LED lights will last you 50,000-100,000 hours before the light intensity reaches 70% (L70) and will save you a lot on energy costs compared to HID lighting.
LED base and heatsink
Choose an LED light that contain a metal core printed circuit board (MCPCB). These LEDs incorporate a base metal as a heat spreader and keeps the chips running at a lower temperature. This is important in extending the life of the LED. The LEDs should be mounted to a thick, finned, aluminum or copper heatsink. Most, if not all common LED grow lights on the market have this quality, so it should not be an issue when deciding on and LED grow light.
LED grow lights sometimes contain internal cooling fans to rid any excess heat that may shorten the life of the diodes. However, only about 15-25% of the energy that LEDs output is turned into heat! This is extremely efficient compared to HPS and MH bulbs that expel 80% of their energy as heat. Some greenhouse and research LED grow lights do not have cooling fans due to the low-heat emitting LEDs and design. This is convenient because the lights require less power since they are not running internal cooling equipment. Some of the grow light brands that do not have internal cooling fans include GE Lighting, Lighting Science, Philips GreenPower, Illumitex, Pro Max Grow, and LTC. Many growers prefer no cooling fans because it is one less part that could potentially break on the unit.