Do you have an opinion which is better the kessil or blackstar. Kessil only uses 36 watts compared to 240 for the blackstar that means blackstar is more powerful light right.
It just means that the blackstar just uses more power.
Kessil lights are nothing like a blackstar, which is just another panel of generic LEDs - may be better than other panels, may not be (I don't know).
Kessil lights are designed specifically for horticulture - they are not made from automotive grade (CREE) LEDs, they are not made from traffic light LEDs, their LED array is designed for one purpose and that purpose is to make Kessil lights.
Not having a blackstar for comparison, I can't compare one with the other.
I can say that I bought lights designed and manufactured (not just assembled) for horticulture and I wouldn't trade them in for a blackstar or any other panel type assembly of generic LEDs.
Kessil lights are low wattage but are designed to have a small footprint and great penetration.
I suppose I do have an opinion about which is better.