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What is the efficiency of PhytoMAX-2 LED grow lights?


The efficiency of LED lights depends on how you measure it. There has been a long-standing "standard practice" in the lighting industry to measure and advertise only the efficiency of the light bulb. Of course this standard was created back when every source of light was a bulb, and connected directly to the electricity coming out of the wall without needing any power conversion. High Pressure Sodium (HPS) bulb makers adopted this "industry-standard practice" and measure all the light coming out of their bulbs- even light aiming at the ceiling away from your plants- to advertise efficiency, but they also ignore the power losses the ballast introduces to the complete system. Measuring the bare bulb also ignores losses from the protective / cooling lens and reflector losses. But because all the traditional bulb manufacturers do it the same way, this method of measurement is still considered acceptable for advertising, even though it is fundamentally flawed.

In the LED grow light industry, many manufacturers have embraced and interpreted this standard when they advertise the efficiency of the individual LEDs in their fixture, giving efficiency numbers as measured when the LEDs are not in the complete fixture. These numbers are provided on specification sheets from the actual LED manufacturers, but they are different for each different color of LED. Since many different colors of LEDs are often used in LED grow lights, many companies simply choose the most-efficient one and advertise that.

In this "industry-standard practice" way of advertising LED grow light efficiency, all PhytoMAX-2 lights have an industry-leading efficiency of 2.4 μmol/J of light, as that is the efficiency of our "bare" IR LEDs. For some of our red LEDs in the PAR region of the spectrum, we can claim a still-industry-leading 2.3 μmol/J efficiency number. But evaluating the efficiency of a grow light by looking at the efficiency of some of the naked LEDs is completely meaningless for many reasons, not least of which is that you are looking at only some of the LEDs in the light. It also does not matter what the efficiency of individual LEDs is if the light coming out of those LEDs is partially lost by having a protective glass lens or "secondary optic" that steals 10% or more of the light. Furthermore, LEDs require direct current (DC), not the alternating current (AC) that is available from the power company. This requires power converters (known in the industry as "drivers") to convert the AC power to DC current to run the LEDs. Inexpensive drivers are not very efficient and can lose a lot of the total power the fixture pulls- the power you are paying for- and never deliver it to the LEDs. So, looking at the efficiency of a single type of LED, or even all the "bare" LEDs used in a fixture, is completely meaningless when evaluating how efficient a grow light will be at delivering light to your plants.

Some of our competitors also do not seem to understand the difference between total photon flux (PF) and photon flux density (PFD). They will use the PFD as measured at a particular point and divide by the number of watts their light fixture draws to come up with an efficiency number. This is completely meaningless because this efficiency number depends on where the light intensity is measured and how it is measured. For example, if we took a PFD sensor 50cm square and placed it directly under our PhytoMAX-2 1000 to capture all the photons coming out, it would see 1602 μmol/m2/s of light; at 1050 total watts this would give an inaccurate fixture efficiency of over 6.1 μmol/J!

The only fair, accurate and completely comparable way to measure the total efficiency of any grow light fixture is to place the entire fixture (including any reflectors) in an integration sphere. These very large, expensive devices capture all the photons leaving the fixture, allowing the true light output of the fixture to be measured- not just the individual LEDs or bare bulbs. But even then, there are multiple different ways of measuring efficiency.

If you count only the number of photons leaving a light fixture without regard to their color (/wavelength), it is possible to make a light look very efficient by having more low-energy photons, because they take less energy to create. In the PAR region of the spectrum, red photons have less energy than blue photons, so you can make more red photons per watt than blue photons- even if the total energy of all the photons is the same! We deliberately include high-energy UV and deep blue photons in our Phyto-Genesis Spectrum® because of the benefits they offer to plants, even though it makes our μmol/J efficiency lower than it would be if we left those colors out.

When the entire PhytoMAX-2 fixture is measured in an integration sphere and only photon counts are considered, the total wall-plug fixture efficiency of our lights is 1.53 μmol/J of biologically active radiation from 350-750nm, and 1.41 μmol/J of photosynthetically active radiation. Of course, what really matters is how well they grow plants. We know we could make a fixture with higher μmol/J efficiency by leaving out UV and deep blue light, but we're dedicated to growing plants as well as possible, not making our lights look good on paper. Even so, PhytoMAX-2 lights are the most efficient grow lights you can buy that provide a truly full spectrum from UV to IR (with actual, significant amounts of UV).