Hello there @SHRED,
I’m gonna answer your questions the best I can.
I think your original question is fundamentally flawed, or maybe I’m misinterpreted it. It’s my understanding you want to cut your power bill down by growing Photo-sensitive seeds.
In my experience, Auto seeds are a bit faster (faster = less light used = smaller power bill). The other reason to grow Autos is to have multiple grow seasons outside, but lets not get into that.
Normally, Photo-sensitive seed are grown because your can increase yield but prolonging Veg time. Doing this will obviously increase you power bill.
A lot of people choose Photo-sensitive to scrog, and this is also done to increase yield.
Scrogging take a little longer, as most scrogged method trim/prune vegetative growth. Any pruning done, may increase yield, but will slow over all growth, so keep that in mind.
Lastly, Autos don’t require 18/6 or 20/4 light in flower. You can decrease your power bill by cutting “light on” hours, after she’s fully in bloom. Again, this may effect yield quantities, as well.