Defenses 2

There are 10 defense buildings available in AE currently
I would like to include Command Centers also to defenses so that makes them 11.
Please let me try to introduce them to you having in mind that all recommendations are not obligatory, most of those recommendations came out of tips and hints provided by legendary wolves like King Kong and Canis Rufus and many others, forgive me for not mention all of them
All values are nominal, you can find them in Tables/Defenses in your browser
Many examples are based on fighters to show the capacity difference per defense easier

Defenses have the purpose to defend your base against attacking fleet. You cannot pul the trigger of them, that means you cannot attack a fleet at your base with your defenses, they will attack against a fleet automatically in case of an attack. You can attack a fleet on your base ONLY with your guarding fleet. Also defenses DO NOT protect your trading routes, you have to keep a guarding fleet at your base to protect your routes otherwise even a scout can commit piracy.
Defenses after a attack will start to regenerate slowly, they stop to regenerate only if your base is occupied and if reach 100% again of course.
In case your base defenses are damaged any NEW defense builded will start with the current percentage stated at your base screen.
Command centers cannot be destructed OR damaged, as soon as you build them they start contribute to your fleet's firepower capacity.
We can split defenses in 3 categories depending on the purpose of them : Turrets, Shields, Command Centers

TURRETS
The purpose of turrets is to inflict damage to the attacking fleet, if someone attacks your base turrets are there to make him regret. Remember that the more fleet he is gonna lose the less profit he will get from your base. If your base is well defended he will either fail either he will lose credits or he will have a marginal profit. Build the best you can and the most you can at your base. As soon as you become capable to build better, replace your lowest with the best possible.

Barracks : Power :4 Armour :4 Shields :0 Weapon :Laser
Their power gives the ability to one set of 5 (level 1) to kill 10 fighters or 5 corvettes and they will die against them.
Totally useless

Laser Turrets Power :8 Armour :8 Shields :0 Weapon :Laser
Their power gives the ability to one set of 5 (level 1) to kill 20 fighters or 10 corvettes and they will die against them.
Practically useless, you might consider to build one set as soon as you settle a base, but better bring some fleet along with your outpost ship.

Missile Turrets Power :16 Armour :16 Shields :0 Weapon :Missiles
Their power gives the ability to one set of 5 (level 1) to kill 40 fighters or 20 corvettes and they will die against them.
Practically useless especially since missile technology is by most players not researched much.

Plasma Turrets Power :24 Armour :24 Shields :0 Weapon Plasma
Their power gives the ability to one set of 5 (level 1) to kill 60 fighters or 30 corvettes and they will die against them.
Since plasma technology tend to be heavily researched you might consider to have some, but IMHO this is not a good turret because it lacks shields.

Ion Turrets Power :32 Armour :32 Shields :2 Weapon Ion
Their power gives the ability to one set of 5 (level 1) to kill 80 fighters or 40 corvettes and they WILL SURVIVE (damaged) against them.
But why they will survive ? Because of their shields
A set (level) of five has armour of 160 but you need to bring along more firepower to kill them because the shields will subract 1.98 power points of each and every ship you bring (with the exception of ion bombers/frigates where ion crosses shields at 50%)
Ion turrets are suggested as traps for fighter drops:
Since fighters will be attracted to hit those turrets, the damage to the defending fleet of the base will be less thus saving your guarding fleet from destruction. Of course they don't inflict a signifficant damage to the fleet but it is a highly recommended turret and i usually build this first after i settle a new base.

Photon Turrets Power :64 Armour :64 Shields :6 Weapon Ion
Photon turrets can inflict significant damage, one set can kill 160 fighters or 80 corvettes and is recommended to build them unless you can build disruptor turrets, mostly because disruptors can REALLY do damage

Disruptor Turrets Power :256 Armour :256 Shields :8 Weapon Disruptor
Disruptors are the best defenses after planetary ring and a must to have on ur bases. With their power a set of 5 can kill 640 fighters or 320 corvettes, and if someone is n00b enough to send 4 dreads alone to attack them he will probably lose them all in his attempt (he will lose 3 for sure and probably the 4th).
Disruptors are really devastating against attacking fleet and are highly recommended. Try to get the research necessary as soon as you can and add them to your base, after that you might decide to disband lower defenses up to photons (with the exceptions of ion if you like to follow the suggestions of those who vote for them)

Planetary Rings Power : 2048 Armour :1024 Shields : 12 Weapon Photon
The ultimate defense, if you can to build them don't waist a minute !!!!
There is nothing better in AE at this moment and with them your Base will make your enemies to look elsewere to find less defended bases. A set of 5 can kill 5120 fighters or 2560 corvettes inflicting huge damage to the attacking fleet. They can kill alone up to 5 Titans if someone send them to your base unescorted or even a leviathan and damage seriously a second one
Have in mind that each planetary ring has equal power to 8 !!! disruptors and 4 times the armour and better shields, so if you can add more sets than one you might consider drop the disruptors.
IMO is good to have 2 p-rings and 2 disruptors at your base, as soon as you can to build a 3rd set of rings you might drop one set of disruptors and if you ever can build a 4th set of p-rings drop the last disruptor at your base. (P-rings don't consume area on your base unlike disruptors, if you follow my suggestion you can use the area for the necessary energy)

SHIELDS
Unlike the turrets, their purpose is not to inflict damage but to increase your base surviveability. Shields have really low power making them not a threat to the attacking fleet but huge armour and shields making ALL your defenses hard to die :
After attack the defenses drop to a lower percentage depended on the damage taken, the next moment this percentage (calculated on total armour of your turrets an shields) is equally distributed to them before the next attack. Shield's huge armour contribute to keep the percentage high after each attack wave and since they have big shield attribute they take small damage.
In conclusion if you have shields on your base, your enemy have either to send a huge fleet to kill them either he will fail or he will forced to repair/attack multiple times if he wants to achieve occupation losing a lot more fleet.
Remember that shiedls don;t really kill the attacking fleet thus they are uselles alone, you have to have turrets to make damage to your enemy or he will kill your lonely shields with repeated attacks.

Deflection shields Power : 2 Armour : 512 Shields : 10 Weapon Ion
Deflection shields can kill just 5 fighters or 2 corvettes (half as barracks ) but they don't die easily. They have better shiedls than disruptors and double their armour. If your base have turrets up to disruptors add some deflection shields too (1 deflection per 2 disruptors IMO)
But if your base has planetary rings it is recommended to replace deflection with planetary shields because deflection has lower shield than rings thus weakening them instead of helping !!!!

Planetary ring Power : 4 Armour : 2048 Shields : 14 Weapon Ion
The ultimate shield, not much to say more
I suggest that u build one of them at your base and upgrade to one more for every two p-ring sets.

TO BE UPDATED .....