These modules will restore capacitor energy.
Passive module which increases total capacitor (and subsequently capacitor recharge rate, which is a percent of to total capacitor).
Active module which replenishes capacitor while expanding Cap Boosters.
Passive module which increases capacitor recharge time.
Boosters are generally preferred for PvP ships since they work well against capacitor neutralizing. For your exact needs, experimenting a fitting tool will show which will serve you best. Compare to engineering rigs and low slot capacitor modules.