Within the horticulture sector you often hear growers sceptical to the new generation grow lights. Many myths surround LED lights and we continue our myth buster series with LED myth #4 - Heat and running temperature.
LED Myth #4 — Heat (Running Temperature):
Heat management could be the killer of horticultural LED lighting.
Without sufficient light, plants are not able to adequately photosynthesize and they will not mature properly. To obtain high light levels, high-watt LEDs at fairly high densities are needed. As light output of LEDs seems to degrade mainly based on temperature of the air around the LED dome. The problem with the current design of LED Grow Lights is the equipment needed to evacuate enough “warm/hot” air from the light and the air exhausts. At this stage, the equipment needed to cool down a high output LED diode is not efficient enough, and the few available are too expensive.
Busted: Thermal management of LEDs is a science in itself. The heat LEDs do generate originates in the semiconductors due to slight inefficiencies resulting when electrical activity is not turned into light. But as LEDs have no filaments, LED Grow Lights are generally more efficient in this area than HPS light sources and, therefore, produce less excess heat in indoor greenhouses.
Proper heat management is critical for LEDs as increased heat affect the performance of the LED in a negative way, effects including a reduction in light efficiency, color shifts and reduction in lifespan of the LED. Since operating temperature is a major factor in the life span of an LED lamp, fixtures require a means for allowing warm air to escape. But as LED grow lights produce minimal heat, it is not necessary for growers to spend a lot of time, energy and expense dealing with excess heat when they can use small and reliable extractor systems for this purpose.
What is the best approach to keeping light arrays cool while keeping costs low?
Water cooling is not 100 percent efficient at transferring heat, at least not yet. Locating the power supply outside of the growing area may give a grower half of the heat savings that could be realized with a water cooled system, but what is gained in lower cooling energy is lost in line losses of long electrical cables.
Including fans (convection) to produce currents of cooling air is an effective way to manage heat issues, but fans introduce a moving part into the system. Moving parts typically break down long before LEDs fade.
However, if you must purchase a unit with fans in it, make sure the LED grow lights have a long warranty and the fans are rated for a lifetime that exceeds that of the LEDs. For example, the fan used in the Heliospectra LX60 is rated to 70,000 hours.