Should I invest on teslas?

Currently a th7 player, should I invest on teslas?

No you have better things to invest money into like barracks,defenses,mine and collectors

Building my second atm, also tH7. Get your mortars to at least level 4 first though.

Nobody can really tell you, it's a personal preference. I wouldn't bother upgrading mines too much for example. Storages sure, but mines ... meh. Above level 7-8 is all I bothered to get to. One or two level 9.

Definitely, a no brainer actually. Mines/collectors past 6 or 7 seem pointless to me. Adding an extra defense vs upgrading a current one is far more valuable.

Yes

Adds more HP to your base and shells out damage.

Yes with teslas long upgrade times it's best to start them early.

Since I placed my first one it's been working a treat. It's a deterrence as much as anything. I have a few attacks in my log where players dropped barbs/arch/goblins on that side, up pops the tesla, frizzles them and the attack ends :D They just give in after seeing it. I don't have it enclosed as that's a give away, but it is backed up by a WT, canon and AT.

it depends on how you intend to use it and how good you are at base design.

Some people hate it cuz of its long built time, single attack. etc.

(though of course you should upgrade your splash damage defences as well).

Anyway, i got mine concealed in the base but i also got 8 other places where it looks like it could be. And lots of attackers look at my low level defences, eager to attack, then pops up 4 tesla at the same place which is likely 80% of attackers would attack (where the townhall side and the weakest side of my base, opposite the motar, also the other side of what looks like a 4 obvious tesla should be :D)

Upgrading tesla is usefull when you want to upgrade your walls too.
That's what I do, 4 builders for long time upgrade (tesla 4 & anti aer 5) and 1 builder for walls.

But before, I have maxed canons, wizards, mortars and other stuff really usefull.

So upgrade first, mortars, wizzards and after teslas & walls.

Concentrate your defense on splash damage first. Teslas can come later (the upgrading that is, but build them if u can)