Rob, I think he also wants some help on how to properly balance the power consuption of the powered systems of the ship...
For that matter, this is what I did when I scripted the HP of my ship. Just got a piece of paper, a pencil, wrote down some values like i'm about to tell you, scripted them in the HP, tested the ship out and it was perfect.
First, make a list of all the powered systems of your ship (that is, all systems that consume power). Cloak and tractors get in as well, just remember they only drain power when activated, and they drain directly from the batteries.
Second, start writing besides the name of each system how much energy it should use per second. Use any method you want to give the values, but obviously with some logic like "this system should drain more power than that one", etc etc. And for the weapon systems, don't remember if you set the power consumption of only the weapons or of the weapon system as well, or both; anyway list them all, weapons and their weapon system. Give the weapons the power comsuption value you want, and for the weapon system that controls those weapons, the sum of the power comsumption of the weapons it controls.
Third, time to set the power attributes of the power generator. You can use Rob's formula if you want, his formulas always help out. The only time I remember seeing Rob making a error in a formula he quickly pointed the "why" to me and fixed it lol
But for the PowerOutput attribute, do this: think how you want your ship: at 100% energy to all systems (that is, ship normally just went to red alert), do you want it:
-to LOSE battery: set the power output to something LESS than the sum of the power consumption values of all powered systems(*).
-consume EXACTLY what power it generates: set the power output EXACTLY the same number of the sum of the power consumption values of all powered systems(*).
-to GAIN battery: set the power output to something HIGHER than the sum of the power consumption values of all powered systems(*).
(*): don't remember if you include the cloak and tractor power consumption values here... I think not but... well... Just try lol
Like I said, with a paper and a pencil, that's a really easy and fast way to balance the power values of your ship(s). I did that with my ship and literally took me 5 mins to do it, 5 more to put the values in MPE.
Now if in the 'Step 3' you want to take in consideration putting some systems at different values than 100% of energy in-game, just bear in mind: the attribute "power consumption" of all the powered systems, and the power output, main conduit and backup conduit capacity attributes are all 'measured' in energy units (EU for now ok) per second.
The "weapons" power bar means the power percentage given to all the weapons, just like the shields bar for all shield generators, the sensor bar for all sensor arrays, and the engines bar to all impulse and warp engines. Example: if a weapon uses 10 EU/s normally, at 125% it'll drain 12.5 EU/s.
I don't remember exactly why that "bars goes off the window" problem happens, but I think it had something to do with exageratedly high values and/or very poor balance of the energy consumption/generation/conduit/batteries values.
Sorry if this became too big, but I hope it helps your (or other peoples) problems regarding setting up a ship's power grid.