Do LED grow lights save electricity?

The Economics Of LED Lighting

The results of the economic analysis comparing the costs associated with LED grow lights with the expense of using HPS lighting include the following:

• For the same crop yield, LED lights cost 75 percent less than HPS lighting.
• Plants can use only 30 percent of HPS light compared with 50 percent of the light generated by LED systems. In addition, 30 percent of the energy used by HPS lighting is lost as heat.
• The typical lifespan of an LED light is as long as 19 years, whereas HPS lights need to be replaced every few years.
• The cost of using LED lights for a 12X12 foot plot is approximately $1,500 per year. The cost of using HPS lighting is a whopping $4,829 annually.

Since the operational costs of using LED lights are a mere fraction the expense of running HPS lights, growers report they quickly recoup their investment in LED lighting systems and then realize significant bottom line improvements in their grow operations.

LEDs are not just a replacement for HPS lights.

HPS and other HID lamps cannot be placed close to the plants without burning them. To maintain thermal control in most instances, grow facilities using a large number of traditional lights need to have a very efficient HVAC system and allow for a safe distance between the canopy and the lights. This increases the cost of construction and maintenance additionally increasing electricity requirements. In contrast using LED lights allows growers to use much more economical facilities. Although LED lights, as every electric device, produce heat, theirs operating temperatures are much lower. They also do not emit heat radiation with their light. Therefore, they can be placed in close proximity to the plant canopy saving space and construction costs.

Bright doesn’t mean efficient.

HPS grow lights appear brighter. This is because they contain a large proportion of green light. Humans see green light about 10 times better than blue or red light. Plants do use green light, but not as efficient as other wavelengths. For plants, a typical HPS bulb spectrum with a high percentage of green and yellow light is a signal that they are shaded by other plants, even if they are not. In such conditions some plants will elongate. Most of the crops grown in this condition will produce less secondary metabolites (chemicals responsible for taste, smell, coloration, disease defence or medical properties of crops).

In contrast, LED grow lights offer a varying and, in some cases, adjustable light spectrum, which can promote desired characteristic in your plants and increase benefits in your crops.

The light distribution matters.

LEDs are constructed to emit light as a beam of light directed down. Traditional grow lights emit light in all directions making them to require hoods and reflectors to direct the light down to the plants. These pieces of equipment add bulk and are not efficient in directing light to the plants  thus indirectly increasing energy consumption.

High quality LED grow lights are equipped with secondary optics. This helps to avoid “hot spots” (a concentration of light directly under the middle of a fixture) and distribute light evenly over the growth area. It also assures that photons are delivered directly to your crop. You should always ask for a light plan. Hanging grow lights in the right position and distance will allow your crops to utilize the photons emitted by your grow light to a full extend.

Energy Costs

If you've grown with traditional grow lights, you know that electricity is often a grower's largest ongoing expense. Although HPS and HID light intensity is higher, LEDs use about half the electricity resulting in significantly more light per watt.

With LEDs, the energy savings alone can quickly pay off your investment, and the longer you own your system, the more you save!

Cooling Costs

Because HID and HPS grow lights run so hot (up to 600°!) both they and your plants must be air cooled with fans and, at times, air conditioning, adding even more energy demand to your system. While fluorescents are a little cooler, they still require external cooling and a watchful eye to avoid burning leaves.

By contrast, LED grow lights are cooled internally so you save money on electricity and can have a quieter, fan-free grow space in the process! And, since LEDs run so much cooler, plants are happy growing closer to the fixture.

Maintenance Costs

While startup costs favor less expensive traditional grow lights, maintaining a grow room full of them can require significant ongoing costs. Apart from the need to purchase cooling equipment, traditional growers seeking peak performance must consistently invest time and money into their hardware as well.

As the key statistic, compare the lifespan of an LED at a conservative 50,000 hours to the 10,000 and 18,000 hours of HID and HPS lamps. What's more, traditional lamp efficiency begins degrading immediately and decreases quickly while LEDs maintain the majority of their potency over their long lives.

Environmental Costs

While saving money on materials, LED growers are also benefiting the environment.

With their quicker burnout rate, not only are HID, HPS and fluorescent lamps adding more mass to the landfill, they're also adding toxins including mercury. And, not only is the lifecycle of traditional lights shorter, the large and fragile lamps are also easier to break during storage and handling, causing more waste and releasing yet more toxins.

As we see all around us, the waste adds up. In the case of fluorescents, you need a lot of those "inexpensive" bulbs per fixture: with a max of 54 watts, a grower might need 10-20 bulbs for a 4'x4' grow tents!