Use of RGB LED strips for MVP


#1

Hi

I have some questions about using RBG LED strip as lightning for MVP build that I’m planning to do. An example could be https://www.amazon.com/SUPERNIGHT-16-4ft-Waterproof-Changing-Lights/dp/B076VG955L/ref=sr_1_24?s=hi&ie=UTF8&qid=1526377352&sr=1-24&keywords=rgb+led+strip. I’m planning to control the light using an arduino and adjust the intensity using PWM. Here comes my question:

  • Does LED strips like this supply enough light? (If I e.g. used 5 m LED strip for an area of 0.1 m^2)
  • Does the PWM harm the plants?
  • Any other concerns with this setup?

#2

I’ve been wondering about that too, but I haven’t figured out a practical way to calculate or measure the light output. I think you would need to build a test configuration and measure its photosynthetic photon flux with a spectroradiometer. But, those are expensive. You could buy a lot of good grow lights for less money than the test equipment.

You could also just try building it and attempting to grow some plants. If you do that, I’d be super curious to hear what happens.

For some related reading on light measurement, check out these threads:

  1. Spectroradiometer that can measure PPFD from LEDs
  2. DIY spectrometry for calculating PAR of cheap LEDs?

Also, you would need to make sure the heat generated by all those LEDs could be dissipated effectively. I’ve wondered about maybe sticking parallel LED strips on a big heatsink, or maybe using some of the aluminum LED channel but leaving off the plastic diffuser that normally snaps over the LED tape.


#3

My concern for these particular lights would be the spectrum output, specifically whether certain colors would be applicable/wasted for plant use.

That aside, if we were to assume it’s similar to full spectrum “white” light, a rule of thumb that’s worked for me is 40-80W of lighting per ft^2. 50W/ft^2 is a good target at the high end, with efficiency of 140 lm/W. Furthermore, the actual wattage draw would need to be measured at the wall, since advertised numbers are often overly optimistic in the LED market.

PWM pulsing/flicker will not have any effect on the plants aside from obvious reduced power from dimming.

As @wsnook mentioned, the best way to determine if light is sufficienct, short of growing out some plants, is to measure with a meter. For full spectrum, you can measure the lumens (because this would be cheaper than a spectro or PAR meter) and convert it (roughly) to PPFD based on lighting type.