How to use our Grow Light Efficiency Calculation Tool to size your grow light
This is a simple and accurate grow light efficiency calculation tool. You can use the grow light efficiency calculation tool for most grow light systems such as CFL, HPS, MH, CMH and LED.
The first step is to use the known PPF/Watt (Photosynthetic Photon Flux/Watt, the measure of light used by plants per unit of energy consumed) of the most common grow light technologies. This information is available from manufacturers data sheets.
Next we estimate the efficiency of the reflector or lens being used in the grow light system. The figures here are likely to range 10% higher or lower for high quality and low quality components respectively. We have used an average in the calculation sheet.
The walls of the grow area are the next critical factor. No walls will result in a lot of lost light. Low quality reflective walls such as matt white or budget tent lining will also result in relatively high light loss. The top tip is to use silver mylar to minimise reflective light losses to only 10%. MIGRO uses a hanging system and lenses to focus 95% the emitted PAR light onto the plant canopy.
The last component is the LED driver or ballast for the HID and CFL technology. The lower quality systems efficiency may be as low as 70% and the best 95%.
To do your own calculation follow these steps:
Select your grow light technology. Example: HPS SE – 1.9umol/watt
Select your ‘Optics’ type. Example: Reflector – 85%
Select your grow room walls. Example: Silver Mylar – 90%
Select your power supply efficiency. Example – Digital ballast – 95%
Multiply the above together to get the system efficiency. Example: 1.9 x 0.85 x 0.9 x 0.95 = 1.38umol/watt
We have tested many different grow light systems and cross checked the actual results with the calculator and the outcomes are very close.
You can use this calculator to accurately size your grow light for your grow area.
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