Right now I'm working with params of ships and I decided to tweak shield regeneration. I want to decrease shield regen. interval to smth. like 0.3 instead of 3 secs and to preserve balance decrease also shield refresh rate values of units of course. Then regeneration of shiels will look more "smoothly" I think. But I realised that energy capacity and energy refresh rate are connected with shields somehow. I've never touched this param. before so I don't know how it works  ???. Please explain me things related to energy... Especially two things: what is "Energy To Shield Exchange Rate" and why interdictor has so big energy capacity - 10000 points, even cap ships don't have so much. 

Energy capacity was formerly used for weapon charging. It is now a vestigal value - no use whatsoever, AFAIK, tweaking just the shield regen value should be enough.

Energy still works in the game it works along with shields. When I use to mod EAW I use to boost ships shields and their regenerators values but it worked really slow. I tweaked the energy's numbers and that made a nice impact.

energy is used for ion cannon effects to the ship. its basically connected to projectiles with energy like the ywings ioncannon shot.