But wait -- There's more!
A lot of the technical jargon is used by companies to take advantage of inexperienced growers that are new to LED. If you are a home grower, all you really need to know is that the company will honor their refund/warranties, that the light works (e.g. there are others growing with the light with photo updates), and that if you use the same product, you should be able to get the same results. Even technical information can be wrong/inaccurate/flawed. What is most important in my mind is that you are getting a good light at a fair price that will lower your energy bill while also lowering the temperature in your grow tent.
Par value is definitely important and you don't want to rely solely on Watts. If there wasn't so much misinformation online and people wouldn't get confused, I would tell them that par is more important than the watts.
It helps to know what the spectrum ranges are as well. Red and Blue provides plants with most of what they need. Others will beg to differ and that is fine. If they want to provide HD photos of their plants growing under their lights for comparison that would be the only way to really show what works better. Otherwise it is all theory designed to confuse people with information overload - when all you really wanted was to grow bud.
Its not mumbo jumbo confusion ....
PAR
Photosynthetically active radiation (PAR) is a
biological term and describes the part of the
electromagnetic radiation spectrum (light) that
is useful for plants to photosynthesize. PAR
defines the spectral wavelength range between
400-700 nanometers (nm), whereas the actual
measurements of the light are represented in
PPF and PPFD.
PPF
Photosynthetic Photon Flux (PPF) measures
the total light output (photons) emitted by
a plant lighting system. PPF provides the
amount of photosynthetically active radiation
(PAR) emitted per second and is therefore
measured in µmol/s (micromoles per second).
PPF however does not provide the amount
that is arriving at the plant.
Photosynthetic Photon Flux Density (PPFD)
expresses the amount of light that reach
the plants per second. PPFD is measured in
micromoles per square meter per second
(μmol/m2/s). Because PPFD is a measurement
of a specific location on the plant canopy, it is
crucial to know the average PPFD on a given
surface.
PPF/Watt
The PPF/Watt ratio provides a clear picture of
the overall electrical efficiency of a plant lighting
system. How much of plant-beneficial light is
converted by the system per Watt? Superior LED
lighting system reach a PPF/Watt efficiency of up
to 2.8 PPF (µmol/s)/Watt, while in comparison
1000W High Pressure Sodium (HPS) can reach
only up to 1.7 PPF/Watt.
PPFD/Watt
The PPFD/Watt ratio is the the most important
term in evaluating the effectiveness of a
lighting system on the canopy besides the PPF/
Watt efficiency. This is the most important ratio
to know as the delivered PPF (PPFD) is finally
important in horticulture and is measured at
least at several points over the plant canopy.
leoLED measurements are taken at 180 spots
on the canopy.
LUMENS & LUX
Lumens and Lux (lumens/m2) are standard
units for the luminous flux of a light source
and are used by general lighting designers.
The luminous flux is the part of the power
which is perceived as light by the human eye,
and is based upon our eye sensitivity at 555
nm. Therefore Lumens and Lux do not provide
a comprehensive picture for horticultural
applications.
Proper research
