My biggest power source so far was 90 hv solars, so about 45K EU/t. 87 of them ran to a mass fab and 3 ran the rest of my base. Wanted to see how crazy you could get with a mass fab, it got so i could almost produce more hv solars just on the UU matter it made each day. Got a bit boring actually, when the world crashed i had made 5 hv solars in just one real world day.
Also had 80 igneous extruders and many recyclers, and the fab would run out of scrap within a minute of the sun coming up. I can see why greg realized that scrap with the regular mass fab was lopsided, it requires less power than his version, but giving it scrap is crazy hard to keep up with.