One of the reasons I never use Light Shields is the stacking penalty.
With the way we all thought armor was working, it wasn’t a viable defensive option for a ship of any class. That left Shields as the only viable defense option for Cruisers and Dreadnoughts. With a stacking penalty of 0.9, you are heavily penalized for mounting multiple shield modules on a ship, regardless of what type they are. Why, then, would you EVER pick a light shield, which has a quarter of the shield strength of a heavy shield, when all that does is penalize the other shield modules on your ship? It takes 4 Light Shield modules to even come CLOSE to the shielding capability of a single Medium Shield, and that’s not even counting the difference in Shield Resistances.
Compared to Heavy Shields, it’s even worse. It is literally impossible to mount enough Light Shields to equal a single Heavy Shield module. You can get to about 96% of the shielding of a Heavy Shield, with MUCH lower resistance, but it takes you 10 modules. Even if you made Light shields cost a tenth of what they cost now, and reduced the weight and power requirements accordingly, they’d still be a terrible choice - because of the stacking penalty and the lack of other defensive options.
In GSB1, the ‘light’ shields for Cruisers had a place - they were good, cheap, low-power shield modules that you could mount on a heavily-armored cruiser to provide SOME protection against fighters and enemy fire. They had a high enough resistance to block fighter weapons and some long-range beams, but the majority of the ships defenses would be centered around armor. With armor currently not a viable defense option in GSB2, that means that players are forced to load up on as much shielding as they can manage - which means taking the modules with the absolute highest shield strength, to offset the stacking penalty.
The stacking penalty is the same as it was in GSB1, but look at your Shield Strength values: the lowest shield strength module in GSB1 still had 100 shield points, while the highest had 275 (albeit with super-low resistance). Most ships that were heavily shielded used some combination of Reflective Shields (for the higher resistance), Multiphasic Shields (for the high Shielding values), and/or Fast-Recharge Shields (for the faster recharge rate). Ships mounting Light Shields still had 100 shield points, while for only a slight increase in fitting cost, you could have a Basic Shield Generator with almost twice the shielding capacity.
In GSB1, each type of Cruiser Shield had something that it excelled at, while being not as great in another category. With the way your shield program combines the shields on a ship (highest overall resistance, highest overall recharge rate, etc.), there were incentives to mix n’ match.
In GSB2, not only are there half as many shield options, but they’re very linear. A Heavy Shield is the best in every category, whereas a Light Shield is the worst in every category.
I think you went the same direction with the Frigate/Destroyer shields in GSB2. You have modules with high resistance and low shield points, and vice versa. That’s a good concept, but they’re suffering because Frigates and Destroyers overall are still crap.
To make different shield modules relevant for Cruisers in GSB2, each different type of shield needs to have something that stands out about it, while still being comparable to the other options in other categories. Light shields are SOOO BAD right now that it’s not worth it to mount them. To bring them back in the game, they need to excel at something. Maybe they’re SO dirt cheap that it doesn’t matter how much they suck, it’s still worth throwing one on a ship for the (temporary) shielding it will offer. Maybe they have a MUCH higher recharge rate than the other shields. At the very least, they should have higher shield strength. A shield strength of 50 can be knocked down by a single hit from some cruiser/dreadnought weapons, which makes Light Shields a highly unattractive option!
I think Light Shields are pretty bad overall, compared to the other options, but I think they’re also falling victim to the distorted in-game environment right now, where every defensive option is bad because a few specific weapons can tear through them all with ease.