capacitor bank

First, Why do you think capacitors need to be installed "in panels"?

may be in some instrument PCB's ?

The basic requirement of capacitance bank in LT panel is your question, I presume.

Majority of industrial load is inductive and that results in low PF . If the PF is not corrected there will be large KVAR (reactive power) that results in loss of power. If the PF is low most of the power companies charge Low PF penalty . To avoid all these capacitor banks are installed with large induction motors and induction heating equipments and in substations to improve PF . The selection of capacitance bank depends on the actual power factor of your system and actual amount of correction . You have to decide weather you need individual compensation near load, Group compensation or compensation centrally. The decision is highly technical job and need real practical experience.