An "old power" Isanth is 25m long x 31m wide and generates 17,500e/s from it's 120 power reactors. I believe it uses a little under 15,000e/s for its 200 thrusters and 80 damage beam modules.
I logged in to the dev build and tried to generate 17,500 power in a 25m x 31m footprint and couldn't...