Hmm, I was trying to optimize the induction matrix pattern when I so the "in series" in the solenoid description.

So with a matrix core, 7 basic converters, 1 basic coil, and 67 solenoids in a long spiral, I can get 4,82Gj of storage. And 19.29Gj using an advanced coil.
As long as the solenoids are"in series", As in, they make a single line, with curve if you want, that is pretty optimal.

Is this the intended mechanic?

old post but in case anyone else comes across this looking for info. as for the answer to your question: sure seems like it!

!!possible spoilers!!
some people just like figuring out arcane stuff on their own, and the mod author clearly wants to keep a sense of mystery around how these things work or he'd explain more.

this might not be all 100% accurate, but from what I've been able to figure out there are a couple of rules:

• coils get a 100% bonus to their innate capacity if there is 1 solenoid adjacent to it (diagonally or orthogonally), but this gets reduced for every single extra solenoid to about 60% when fully surrounded.

• every solenoid "in series" adds to a matrix wide bonus to capacity, where "in series" is defined as having no more than 2 other solenoids touch each other orthogonally. any solenoid that is touching more than 2 others (orthogonally) gives no bonus and is likely to harm total capacity. diagonal adjacency is fine.

• there is an 100% extra bonus for having exactly 48 solenoids. this bonus gets slightly reduced for every solenoid less or more than this regardless of your maximum tile size. because of this a superlong chain of solenoids gets less and less effective as you add way more than 48 of them. it seems that adding more than 71 in total isn't worthwhile, making the upgrade from 100 tiles max to 144 tiles max not all that useful imo.

the main takeaway from this is that a solenoid tile gives equal capacity to a coil in straight series.
also, the capacity added by each solenoid depends on the average capacity of all coils in the matrix, so having a single one that has the full 100% bonus is likely ideal. adding more can tank overall capacity if it harms the average per coil capacity.

here is an example of a cheap way to get pretty good capacity: https://imgur.com/0laL4Gc (21.8GJ, 6 advanced transfomers=1024MW IO)

you can of course add more coils and end up with a higher capacity but it won't improve by all that much compared to the cost of the coils.

here is an example of a cheap way to get pretty good capacity: https://imgur.com/0laL4Gc (21.8GJ, 6 advanced transfomers=1024MW IO)

I placed solenoids a long diagonal line. I have 6 advanced transformers + 1 davanced coil + 50 solenoid in a long diagonal line. It gave me ~21.7GJ.

you can of course add more coils and end up with a higher capacity but it won't improve by all that much compared to the cost of the coils.

Indeed. 1 coil is optimal. If you need more capacity you can just build another identical matrix.

it seems that adding more than 71 in total isn't worthwhile, making the upgrade from 100 tiles max to 144 tiles max not all that useful imo

I think the extra tiles are intended for extra transformers. However with the transformers stacking exponentially, there is no need for so many of them. I think they just shouldn't stack exponentially, maybe make the IO (x+1)^2 MW. This will make the extra space provided by T3 matrix useful, as the T3 coil adds a lot of capacity.
Right now Superior transformers are not needed either, advanced are already enough.

Another problem is, with fusion unlocked, induction matrix has a very strong competitor: fusion steam tanks. A maxed matrix can store ~210GJ, and a vanilla tank of fusion steam can store 1TJ. The silo tank from the addon can store 8TJ. I think the matrix still wins by IO, but no longer useful for long term storage. Steam tanks are just dirt cheap and also take less space.

It looks like the logic has changed so they don't seem to work this way anymore.