Investing in LED grow lights is bound to pay off over time due to the lights’ low energy consumption, low heat emission, and light spectra optimized for efficient plant growth. However, the investment may prove to be wasteful if the crucial step of light planning is executed improperly.
The Myth of the LED Watt
If you’ve been researching the best LED grow lights for more than about 30 seconds then you’ve probably noticed that most manufacturers give each of their models a Wattage rating. At first blush, it may seem like the more Watts you get for the fewest dollars the better. Unfortunately, for most of the LED grow lights on the market, even several of the ones we recommend, those numbers are simply not accurate.
Often times they represent the max output of the LEDs in the light, but these lights are very infrequently capable of outputting anywhere near those numbers. (example; A 3W LED is typically run at 1-2W to extend the life of the LED, however, many manufacturers put 100 3W LEDs in their light and call it a 300W light). Add to that the fact that the wattage numbers are, theoretically, simply a measure of the energy going into the light, and not a measure of what is emitted by the light and you have a bit of a conundrum.
LED Grow Lights Have Fewer Heating Issues
It’s important to understand a few more things. First, a light’s outputs are both heat and light when energy is the input. Light is what we want, not heat. The more heat a light puts out then the less light it is putting out from the same amount of energy input. This is why traditional forms of lighting (Incandescent, High-Pressure Sodium, etc.) get so hot and are so inefficient. LEDs save energy because they don’t get as hot. Pretty simple, right? However, some LEDs get hotter than others and some emit less useful light colors than others (more on that later). This makes it very difficult to make an apples-to-apples comparison between LED grow lights. HPS grow light may not so less heat.
“That’s why we always advise our clients that LED Watts are on the packaging to server mainly for marketing purposes,” says Mathias, a tradesman at the Fantastic Electricians (London).
Ultimately, we will use estimated Actual Watts for our comparisons, since Claimed Watts are unreliable, and accurate output data is not available for many of the available lights.
How to Measure LED Grow Light Efficiency？
LED grow light efficiency in umol/Joule (400-700nm) is often stated as micromole per Joule -- or seen as umol/j or PPF/W--means for every joule of electrical energy (Joule = watt x second) a number of photon micromoles are produced. Most entry-level LEDs are between 1.0 and 1.7 umol/j. Higher end LEDs are usually 2.0 umol/j. 400-700nm relates to the wavelengths of light in nanometers (nm). 400-700nm is the spectral range that plants use most efficiently to photosynthesize. This range is also often referred to as the range of Photosynthetically Active Radiation (PAR).
How to Choose a LED Light for Your Specific Setup Using Watts?
As a general guideline, you should try to get a minimum of 50 watts per square foot with a LED grow light. This guideline is by no means perfect but will help to get you started.
50 watts per square foot means that:
A 400W LED grow light will cover a 2.5 X 2.5 ft space.
A 900W LED grow light will cover a 4 X 4ft space.
A 1600W LED grow light will cover a 5 X 5ft space.
Ways to improve
Monitor Light Levels for Energy Efficiency in Lighting
Most commercial growers have a system in place for measuring light quality across the canopy.
If you don’t already, consider acquiring a quantum sensor. This device measures PPFD. Of course, you should already have access to PPFD specs from your lighting manufacturer. But what we’re talking about here is monitoring light quality over time and within your unique marijuana grow tent.
Many cultivators use sensor measurements for light mapping. The process of light mapping involves measuring light at specific areas of your grow room to monitor uniformity and light intensity. This allows you to catch inconsistencies and make adjustments. Those adjustments could help you better manage energy efficiency in lighting.
For example, an overlap in light footprints could create a hotspot. If you can eliminate that hotspot by spreading out the lights and even eliminating extraneous lamps, you save energy.
Hanging heights also play a major role in PPFD. Proper hanging heights for HID bulbs are less adjustable due to their high heat output (you don’t want to burn your plants).
But you have more wiggle room with LED lights. And if you find that your canopy isn’t getting the amount of PAR it needs, a lower hanging height does the trick.
Of course, this would only result in energy cost savings if you can lower the light and reduce intensity. But efficiency isn’t just about using less; it’s about eliminating waste. If your lights are too high, you might be wasting perfectly usable photons as light intensity depreciates when light escapes off the sides of the canopy.
Keep Grow Lights Cool
You may already know that LED grow lights emit almost no heat. This is another reason LEDs are the top choice for energy efficiency in lighting. Less heat radiation means less need for supplemental cooling—another major energy expense.
However, a lesser known detail is that high heat can limit efficiency and reduce the lifespan of a luminaire.
The best LED grow lights come with features to prevent overheating within the fixture. We designed our SolarSystem series with user replaceable fans and a housing that promotes heat dissipation. These features help us achieve the expected 100,000-hour lifespan for this unit.
Beyond light selection, you can help promote energy efficiency in lighting by maintaining a safe temperature for your lamps. Keep the thermal junction temperature of an LED light below 100 degrees, and you’ll get the biggest bang for your energy bucks.
Keep Up with Innovations to Improve Energy Efficiency in Lighting
Finally, stay informed.
The science of cultivation shifts constantly. We are always making new discoveries about what plants need. New findings allow manufacturers like us to engineer lights that don’t waste a watt on photons your crop doesn’t care about. This information also guides you through decisions about which type of grow light to purchase and how to program your light spectrum.
Technology is also advancing at a faster-than-ever rate. We’ve met a lot of growers who have taken years to get onboard the movement toward LED lighting. Why?
Because they were still working with old information. They didn’t realize how much LED lights had advanced in efficiency, intensity, and overall function.
If you think it might be time to improve your energy efficiency by switching to LEDs, we recommend visiting California LightWorks. We use top shelf LEDs by industry leader Osram. Our SolarSystem series allows you to customize your light spectrum, so you can ensure your lamp only produces the light your crops need.
Final thoughts
Indoor gardeners didn’t use to have as much choice in artificial lighting as they do today. In fact, it used to be sunlight or nothing. After incandescent came fluorescent. Others followed, but the one that’s really making waves is the LED. You can find full spectrum LED grow lights at affordable prices, and they have much longer lifespans than their predecessors. Also quantum board led grow light with high watts can be a great choice. Unlike other artificial lighting, LEDs don’t run hot at all – and even the big, powerful ones typically include heat sinks (like your computer or laptop) that help absorb any extra heat. On top of all those pluses, LED grow lights are also energy efficient, and kind of cool looking.