How do the different sizes of modules compare to eachother?

Is there an equivalency between some number of small modules and medium/large/huge?

Does 3 small modules equal, in terms of effect/damage, a large perhaps? 2 a medium?

Perhaps it scales instead?

Solution 1:

Module damage scales with size by following relation:

Weapon Size Damage
Small       100%
Medium      150%
Large       225%
Huge        337.5% 

Two medium weapons is better than one large. Double turret increase damage but decrease range.

Source: SPAZ wiki

Solution 2:

Two modules of one size will do more damage than a module of the next size up, but will have a shorter range.