I'm going a run with Exotic Industries, and one of the dependencies is this mod. I'm having an issue trying to get the Solar Laser Tower to actually work. I put it down, along with 50 of the Heliostat Mirrors, but the tower never seems to fully charge. I've left it there for several minutes, and nothing. I'll see a beam between the tower and mirrors from time to time, but nothing consistent. It just sits there with the low fluid and never fires.

Here is a screenshot https://imgur.com/01CApRV

The laser towers work the same way as the power towers; the fluid does not charge over time, it just represents the current intensity of sunlight, which scales their damage past the activation threshold.
There is a bug report that the beams are not appearing that I haven't had time to look at due to work, but it may also just need more mirrors - the max for any tower is in the range of 450, so something like 200 is generally safe - this effectively has not been balanced for the laser tower.
When it's activated, it will work like a very powerful laser turret.