AsNoriuanswered grow question 3 years ago I just finished 17 auto run under 4 X 240 W quantum's( one was limping, working only half power) Smallest plant 32 g, only 5 below 50g plant , at the moment 92 g biggest, but I think at least 3 will brake 120+.
So by theory not bad , around 800 W and I'll have 1.1-1.3 kg.
I grow organic in soil, had holidays, so I believe with better training results could be higher.
Check my first diary here. I finished 9 plants under 2x240W quantum's.
There is chat here, you need honest opinion - text me there.
Good luck in Your adventure !