If you haven't played SFB (and I know I haven't), they work like this:
They're fairly similar to normal shields, but with several huge advantages: They power up instantly, have much better strength per hull space, and much faster regeneration. I think they also have different EM signature characteristics when damaged, but I'm not sure about that. They also have one minor disadvantage and one potentially serious one: small amounts of damage will leak through, even on the first hit (I'm not sure how much), and if they get beaten down and then destroyed by internal damage, they cause massive secondary explosions. Also, I think each component is 10 HS instead of 1.