April 12, 2022

LED UV grow light Vs Fluorescent UV grow light

By Shane Torpey
LED UV grow light  Vs Fluorescent UV grow light

Why do I still sell UVB fluorescent fixtures when there are UVA and UVB diodes available on the market?

To demonstrate the difference in performance I compare a 100 watts LED UV bar grow light and a 20W UV fluorescent grow light for UVB and UVA output.

The LED bar is a 100W2 x LED bar package from Mammoth lighting and includes UVB diodes (310nm) and UVA diodes (395nm). There are about 15 UVA diodes to every 1 UVB diode delivering the spectrum output below.

Mammoth UV LED bar spectrum


The MIGRO UVB 310 Fluorescent emits a spectrum range from 280nm through UVA and into the visible range.

MIGRO 310 UVB spectrum

I first tested each fixture for UVB output in a 5x5 or 1.5m x 1.5m test area at 40cm hanging height.I used the Solar Meter UVB sensor with a sensitivity range up to 320nm, just before the start of the UVA range.

Solar Meter UVB sensor


The 100W UV LED bar delivers an average of 6µW/cm² over the test area.

Mammoth LED UV bar UVB output test

The MIGRO UVB 310 is only 22W consumed but delivers 7 x times more UVB than the LED fixture.

MIGRO UVB 310 UVB output

The UVB LEDs are only about 1/15th or about 6 to 7 watts of the total output so the UVB output per watt is quite high but the total amount of UVB delivered is low compared to the 22W UVB Fluorescent.

I then tested both fixtures for UVA output using the Apogee SU-200 UVA sensor with the following sensitivity

Apogee Su 200 UVB sensitivity range

The Mammoth LED bar delivers an average UVA output of 576W/M²

Mammoth LED bar UVA output

The MIGRO UVB 310 emits an average UVA intensity of 217 W/M².

MIGRO UVB310 UVA output

The MIGRO UVB 310 emits about 40% as much UVA as the Mammoth LED bars but only consumes about 20% of the power. Therefore the MIGRO UVB is over twice as efficient in delivering UVA to the plant canopy as the LED bar.

The 100W LED bars cost 2 to 3 times as much as the 20W UV Fluorescent fixtures but are much less efficient. My conclusion is that UVA and UVB LEDs are not yet effective or cheap enough to compete with fluorescent technology.

Buy the MIGRO UVB 310 here



Category_Grow lighting tips grow light spectrum Ultraviolet