KMC's Analysis of Large Shields (SPECULATION)
Before we did in, this is all subject to change at Walt's whim. Some of this is based off opinion. If you have anything to add please let me know. This analysis does not account for resource costs which will be important in the full version single player. People have questioned if having a smaller arc would change shield strength, Walk has said no(in my sources). I would also like to point out that on current shields, if the arc is covered by a block the shield has no reduction in HP.
Scroll to the bottom if you just want the quick conclusion.
Data:
- Current shield: 15,000 shield HP and 4,000 block HP, Arc of 90deg.
- Small(Internal) shield: 15,000 shield HP and 6,000 block HP, Arc of 90deg.
- Large(external) shield: 45,000 shield HP and 18,000 block HP(block HP assumed to have the same 3x increase), Arc of 160deg.
Sources:



Walls
The most packed shielding for walls today usually looks something like this:

That is one shield for every 3 blocks of frontal area, 5,000 shield HP for every frontal block. If you look at one block on the wall to see what focus fire will do, you either have to go through 3 or 4 shields to get to the block. That is 45,000 to 60,000 shield HP to penetrate. With the full version a wall can be looking very different as shown in the following images.
Here is a very packed wall, with an average of 9,000 shield HP per frontal block, though it has one problem. It only covers ~ 80% of the wall. Making it not very usable. In order to penetrate you either shoot in the gap or go through 45,000 shield HP. It has a ratio of one large shield pre two small cannons protected, not very good.

This next set up does not leave any gaps, if you have seen my questions on discord about weaving shields. This is it. It averages 9,000 shield HP per frontal block. If we assume large shields cost to HP ratio is the same as our current shields and use the example of current shields to compare, here we pay three times as much for just under two times the coverage, while leaving shields exposed and losing 40% of the gun space. At any point this layout takes either 45,000 or 90,000 to penetrate, this is very good against burst damage. Given the gun density, this setup is 120% more effective than my current wall example for three times the price. Aka it's 40% as cost effective as the current wall example. Not cost effective. Not to mention the cost of making a ship wider to account for the lost guns. And then the cost of adding more thrusters to gain the agility of the smaller ship back.

This next setup has 3,750 shield HP per frontal block, less than the 5,000 in my current wall example. It still loses gun space and has exposed shields. Need I say more? Well actually I do need to say more. The damage needed to penetrate any one position is 90,000.

Conclusion
Large shields have many disadvantages and won't be as effective as hoped. They take up to much frontal space to be used as a main defense. But adding a single layer of large shields can be very beneficial to walls just about doubling the damage needed to penetrate any one point. Large shields can be very useful in ion and rail barrels given that they can stop shield stacking from reducing frontal armor around barrels.