Choosing a new LED grow light can be a bewildering task. However, if you are not careful you can end up choosing an LED light that delivers insufficient photosynthetically active light to the actual plants, as some manufacturers use low quality LEDs that were not designed for use in grow lights or are operated inefficiently overcharging them. We have compiled this list to help establish facts for your decision making.
1 - Grow lights don’t need high power
LEDs are light emitting diodes that turn a current of electricity into a certain amount of light radiation based on their constituent alloy. Therefore, electrical current sets the light output for an LED, and a typical operating current is between 25-100% (100% being the maximum current); at 100% the LEDs are inefficient and waste heat, but at 50% of maximum current, efficiency is reached producing good PPFD/W. Many high power LED grow lights use LEDs at a high current, which reduces lifespan and reliability through increased heat generation. At leoLED we factor in longevity and light quality by running LEDs at very low current to deliver the most PPFD/W.
2 - PPFD/Watts are more important
PPFD (Photosynthetic Photon Flux Density) is the useful output of the grow light in the sense of producing photosynthetically active radiation. Plants typically use between 100-1000µmol/m2/s PPFD, therefore maintaining evenly spread and high level enough is the main aim of a good grow light, as photosynthesis and other plant functions will be stimulated. Therefore, using measured PPFD compared to the power consumed indicates the actual performance of a light, providing the light reaches the plants well. LED grow lights - when designed well - can achieve PPFD/W ratios of 2.9, up to 30% higher than HPS.
3 - Extracting all that extra heat is a hassle
At 1000W, a low quality LED growlight can be an electric heater. To stop overheating the light unit and growing space you need extensive heat extractor systems, just like you would if you used HPS or Metal Halide lights, removing a lot of the benefit of using LED lights in the first place. Fans can fail and lead to component failure! Passive cooling is much more advantageous and cheaper in the long run. In addition the heat disspitaed by the passively cooled heatsink can be used to bring some heat into the closed environment.
4 - The light pattern will be unequal and concentrated
Such high wattage in a light entails that all the power is consolidated into one unit, meaning the light produced will be from more or less one point. If you see your infographic on LED vs HPS vs Fluorescent vs Plasma, you can see common light patterns from grow lamps. A 1000W LED lamp would be similar to that of Plasma or HPS lights and not the best for growth, whereas multiple smaller wattage LED lamps with high PPFD output would give quality distributed light to your crop, perfect for vigorous and equal growth and flowering.
5 - High cost
If a grow light is 1000W, it is either poor quality and inefficient, or high power for a very large space. Some poor quality LED grow lights use generic LEDs and inefficient LEDs that consume a lot of power and provide insufficient light output. Running such a grow light at 1000W will cost a lot through electricity usage over the years when a better quality lower power LED light could do a better job for less. Most growers are better suited by lower wattage LED grow lights spaced out over their crop at a height of 20 cm - 60cm, where light is spread optimally. In the long run, LED technology comes at a significantly lower cost of ownership.