What is a PAR LED light meter plus how is it different from other light meters?

So it’s great if you’re interested in growing plants. Because then a PAR lighting meter can be one of the most useful tools that you’ll ever need. However, just like any other tool, it’s best to understand that the PAR lighting meter also comes with a few limitations of its own. PAR meters were designed with a sensor that counts the individual particles of light or rather counts each photon individually.

PAR is simply the photosynthetic radiation needed for growing plants. It usually occurs between the range of 400nm to 700nm. PAR is basically the slang used within the horticulture world as it applies to light. However, it should not be thought of as a metric measurement but one that defines the appropriate light for photosynthesis.

Sensors weren’t made to be perfect, and some easily record the wavelengths of light better than others, and the spectroradiometer PAR meter solves this inaccuracy pretty easily. This is done by breaking the light into constituent wavelengths. These wavelengths are simply the different colors that are sued to measure light. After being broken up, the photons per wavelength is then measured, followed by the per-wavelength correction. 

Measuring PAR

This correction factor is usually determined when the device was calibrated with another source. Thus far, this is the leading accurate method for measuring PAR. However, spectroradiometers are more expensive than others and might be more than what some people intended to spend. 

There are cheaper PAR meters that make use of single light sensors. A filter is placed in front of the sensor so that it will only be able to see those within the 400nm to 700nm PAR range. With these devices, the accuracy is dependent on filter material and how well it works. There are better quality filters, but they may cost a ton more, which increases the overall PAR meter price. 

Since these devices are nowhere close to perfect, they are usually calibrated using the typical or average light spectra. PAR meters in this category usually tend to have two calibration settings for both special electric types and natural sunlight. They can also determine common light sources’ total PAR value, and they do so pretty accurately. 

In areas of highly concentrated spectrums, the sensor or filter material becomes inaccurate. This then simply results in the PAR meter producing an incorrect reading. Additionally, PAR meters have also been known to measure the light that comes from LEDs inaccurately. So if you’re interested in growing plants, you should always do proper research before setting up your lighting system. 

Before you set up your system, you’re going to want to think about some of the following questions:

1. How much PAR can your fixtures produce?

2. How much of the PAR available is instantaneous?

3. How much energy is consumed to create PAR for your plants?

The above comes from the fact that canopy plants absorb more red light while they tend to scatter deeper red light. Hence, the light above 660nm will begin to increase as you’re taking measurements. This applies to anywhere under or within a close distance to the canopy. Since this occurs, PAR meters can easily under-report the true values of PAR within the area. 

In essence, companies have started making lights that actively work to grow plants better. As you evaluate your plants and the PAR readings, it’s best to remember that they will use some outside light. This means that they will utilize light that isn’t within the PAR spectrum. So if you’re interested in purchasing a PAR meter, it’s best to select one that isn’t within the typical spectrum according to this PAR Meter Website.

There are PAR meters that also include infrared and ultraviolet in their calibration. Hence, lights are crafted to ensure that plants grow to the best of their ability. There are also some companies that designed meters with multiple lenses and even reflectors. This significantly narrows the true PAR value and takes the attention away from the footprint.  

If we’re looking at the difference between a PAR meter and other light meters, it’s quite simple. Other light meters were created to measure normal light or rather Lumens. This is the measurement based on our eyes in an appropriate environment. PAR meters are used for measuring the light as it applies to plants and the spectrum that they flourish in. 

As we conclude, we have just looked at PAR meters. So if you’re interested in growing plants, you should consider adding a PAR meter to your list of tools. PAR meters are accurate and effective at determining how light is distributed among your plants.