HID vs. LED
HID, short for High Intensity Discharge, are lights using gas discharge to emit light, which has been dominant in the market for decades because of its advantage in raw material cost and mature technology. But now it seems a new star - Light Emitting Diodes (LEDs) will put an end to that situation. How? This leads to another question, what can you benefit from LEDs?
1)50% cost saving.
To discuss this, we need to mention the Light Efficiency, namely the quantity of lumens created per watt of electricity. Nowadays LED can reach 200 lumens per watt while the best HID can only be around half of that. So in this way, LED will save you significant power in the long-term run, which is a one of the major cost in projects. With no doubts, the old HIDs will fade away and new leading LEDs will show up and keep rising in the future.
HIDs produce more heat because of its working theory, about 4/5 of the power consumption is released as useless heat, especially in the form of Infra-Red (IR) radiation. To keep the environment cool, you need a lot of extra air conditioning fixture, which further cost electricity. What’s worse, this IR radiation will harm the plant leaves anyway even if you control indoor temperature down at a reasonable degree.
In terms of LED, There are no such questions since it emits only half of the heat compared to HID. And moreover, its heat is well radiated through the heat sinks in the back, thus no damage to the leaves.
3)Specific Spectrum and Programmable.
In Biology we know plant fuel themselves through Photosynthesis, in which two pigments contribute the most, namely Chlorophyll a and b. And many science studies have showed that Chlorophyll absorb Blue and Red spectrum the most, which proves its exact need in the process.
However, considering the situation of HID, they can only provide a mix of all the bands and will never be specific to meet the plants need. And the other problem is spectrum demand varies in different plants and growth stages (say seeding to harvest) even for same plant.
Will LEDs handle it well? The answer is yes. Because LEDs use a lot of various diodes, which allow it to produce different yet narrow spectrum bands to feed the plants. And in the market, you can see Blue, Red and mix of them or even white LED grow lights. So you got a lot of choices based on your grow need.
The HIDs degrade over 10% one year, and one of the bad effects is spectra shift, making its spectrum less efficient for your plants. So to keep the yield, the experienced growers change HID bulbs or lamps at least once a year or even twice, which is very troublesome and expensive. However, things are quite easy when it comes to LEDs since it has 50000 hours lifespan on average. So no bulbs changing, no extra cost in labor and less danger, which together make it cost-effective in general.
So in fact HIDs cost much more than LEDs even if it is much cheaper in materials. And LED grow lights with its increasing advantage in every aspect will replace the older HIDs gradually in green house, indoor growing and plant research center.