The most accurate measurement of a lights output power pertaining to growth is the amount par light. This is measured in micromoles of photons per meters squared per second(umol/s) from the light within the par spectrum. Even though an 1000w hps puts out slightly higher par than most LED's, only about 70% or so of that light is used by the plants. This is where LED's are more efficient and productive. They focus on only the areas(blue, red, and little white) of the par spectrum to maximize growth, letting the plant us over 95% of the emitted light. The higher the par output, the more intensity the light has to penetrate with no matter what type of source...all light follows the inverse square law...twice as far away gives 1/4 the power.
I use 2 Apache techs...I love them and so does my monthly bill. Just finished my 4x4 tent with 10 plants in 2 gallon soil. one week veg...1.43oz/plant yield. Emerald triangle's super sour OG...very short , no stretch...shouldn't have toped them they were so short but good yield anyways. Each light has 120w of leds pul 2 fans and drivers, pull 158w each so only just over 300watts.
Par Outputs to Know
The Sun = about 2000umol/s
1000w hps = 1700 umol/s @ ??? no distance stated. My own testing shows about 1540+ with my lumatek 1000 and the quantum meter @12"
Apache Tech LED = 1050+ umol/s @12"
Optimum Par level for average plants = 500 umol/s...we all know our special plant wants more than this.