Confused about HPS watts versus lumen ratio

[SensiStarFan]

Hi all!

So a 400 watt HPS will put oout 45,000 lumens. A 600 watt HPS puts out 95,000 lumens. And a 1,000 watt HPS puts out 145,000 lumens.

This means a 400 watt HPS produces 112 lumens per watt. A 600 watt HPS produces 158 lumens per watt. And a 1,000 watt HPS produces 145 lumens per watt.

So I have two questions. First, did I leave something out in this consideration or is a 600HPS in fact more efficient than either a 400 or a 1,000? Secondly and probably more difficult, can anyone tell me exactly why the efficiency is different for different watt ballasts?

-SSF-

 

[The Hemp Goddess]

I do not know why the efficiency of the lights differs. However, you are correct that the 600W is the most efficient.

 

[OGKushman]

E= output over input. Efficiency is dependant upon internal friction of the system. In this case heat added per watt drawn.

The formula would take a long time to determine the variables. But basically the 600 watt system is easier to cool per lumen/per watt. This means less energy is lost to heat transfer