How to compare grow lights?

How to compare grow lights?​

• PAR – Photosynthetically Active Radiation – 400 nm to 700nm.
• PPF – Photosynthetic Photon Flux – tell us how much PAR a light source emits per
  second.
• PPFD – Photosynthetic Photon Flux Density – amount of light deliver on a specific
  location per second.
• DLI – Daily Light Integral – Amount light require for a particular plant per day.
• PAR meter – A devise measure PPFD, unit of PPFD is μmol/m2/s.
• Spectrometer – A device shows the relative intensity of different wavelengths, which
  is used to compare different spectrums.

To compare different grow light, you should understand basic metric units of horticultural
lights and its measuring devices.
To protect from misleading information, marketing claim from different company, customer
should learn and understand above basic information.

1. Check PPF value of grow light

PPF value mentioned in μmol/J, high PPF value indication of better grow light.
Lumen is not a unit of comparison; lumen is for human vision.

2. Check wavelengths of LED chips

It is very easy for companies to mislead potential customers by saying horticulture
grade LED chips, dominant led chips such blatantly wrong metrics.
While comparing basically check differant wavelengths used in light fixture such as
Blue -450 nm, Red – 660 nm, UV – 390 nm, IR – 730 nm as each wavelengths has its
own role in photosynthesis process.

3. Compare spectrum graphs

As per plant requirement, check and compare spectrum graph. Understand percentage
of difference wavelengths and its purpose.
Many scientific papers and absorption theory confirmed that most useful wavelength
for plants are 400 nm to 700 nm (PAR range). Apart from PAR range, many new
study show that UV & IR wavelength also has importance for difference pigments.
Plants has numerous pigments and photoreceptors which absorbs different
wavelengths, so it shows that green and other wavelengths also has its own
importance.

4. Check PPFD chart for single light.

Ex. If you are buying 4ft grow bar then ask manufacture provide spectrum distribution
for 4ft x 2ft area from 1ft height.
Don’t just compare single reading at center, ask for complete PPFD chart for
particular area.

5. Check power consumption of light

As operating cost of farm is one the important cost while running any farm. And
electricity consumption of grow light plays vital role on operating cost.
Lower consumption and more PPFD is key for grow lights. Check with supplier unit’s
consumption for a day by considering fixed photoperiod.