Been meaning to throw this up for about a week, been busy.
Alas here it be.
Figured something out when upgrading my trasformers the other day.
In a nutshell.
Grid loops are bad, because the way in which IC2 power works is backward requests from the machines to the transformers up the line so on and so forth, when you have loops the requests get lost and the machines start complaining they don't have enough power.
I had 1 MFSU 2 MV transformers and 8 LV transformers, machines were running fine, when I added the second bank which effectively doubled the power line from 256 to 512 machines started complaining, because the loop blocked the request for power even though I technically had a 512 line @ 32EU/tick
To get the full output from an MFSU you need 4 MV transformers and 16 LV transformers. Which will give you 512 EU total shared over your 128 EU/ tick and your 32EU/tick lines.
4:1 Ratio
1 MV and 4 LV would give you 128 lines
2 MV and 8 LV would give you 256 lines
3 MV and 12 LV would give you 384 lines
Of course there are many ways to do your power grid, I personally find this easier than throwing transformers around as needed, I know exactly how much power I have and can easily calculate how much power my machines need.
The transformers can be in a line, go around a corner or snake back and forth, as long as there is no loop in the system there should be no problem with lost requests.
Examples
A good wiring job with no loops.
A bad wiring job with grid loops.
A good solar array with no loops.

A bad solar array with grid loops.
My machine shop runs two MFSU's through 8 MV's then 32 LV's which gives me 1024 lines, more than the combined total of all my machines can pull even with quad overclockers.