LED grow lights have come a long way in a very short amount of time. Manufacturers first started using 1/16th Watt diodes and then used larger and larger diodes as the technology advanced. Now you can find diodes even up to 50 Watts and larger, but is bigger always better when it comes to LED growlights? The answer is No. The ideal diode size for LED growlights is the 3 Watt diode.
Although 1/16th Watt diodes are too weak to grow much of anything and 1 Watt diodes by themselves do not penetrate enough, diodes that are too large are also counterproductive for indoor growing. Save the 10 Watt diodes for street lamps. They have no business going into grow lights as they are much more expensive on a $/Watt basis, give off more heat and completely defeat the whole purpose of growing efficiently with LEDs.
The ideal size for LED grow lights are the 3 Watt diodes. The 3 watt diode provides the ideal balance of canopy penetration without having excess heat problems that come with larger diodes. With 3 watt diodes, a grow light is able to penetrate up to 5 feet past the plant's canopy which is what is needed for commercial indoor growers.
What are the drawbacks of using 5Watt, 10Watt or lareger diodes in a grow light? The first issue is heat dissipation. As the diode size increases, so does the amount of heat that needs to be dissipated by the diode chip. Larger wattage diodes need larger heat sinks to dissipate the heat that they give off. This results in heavier and bulkier lights. The second issue is of chip density. Since the 5Watt and 10Watt diodes give off more heat, they must be spaced further apart to avoid thermal failure. They cannot be packed as densely as the 3 watt chips. The result is a less densely packed grow light that is heavier and bulkier.
The third major drawback of the 5Watt and 10Watt diodes is that they are too expensive. They cost more and are also more expensive on a $/watt and $/ square foot basis. A quick analysis shows that it is not worth paying a premium to have larger diodes in LED grow lights. They are unnecessary for indoor growers and come at a burdensome cost of increased prices, less densely packed network of diodes, and bulkier grow lights.
Bigger is not always better. When it comes to the question of the ideal diode size for indoor LED grow lights, the 3 watt diode is the smartest choice for any indoor growing project.