Add an EPS console that gives a bonus + to power transfer rate. It doesn't actually boost transfer rate, as there is technically no transfer, what it does it boost power regeneration rate, including weapon energy regeneration after you fire weapons. General rule of thumb- for each phaser over two you equip, you'll want a +1 total bonus from said consoles to keep your power levels at a level as if you were firing only two phasers. However, that's not an exact rule, and the more phasers over two you go, the less it stands true.
You can also juggle the firing to time it with the ship's natural regen.
I haven't found a way to outfit my cruiser with four beam arrays...only three plus a torpedo or mine launcher. It's strange because with three beams going I stay at max weapon power (or close to it) 100% of the time, but as soon as I equip a fourth phaser array in that torpedo slot I have zero energy to fire anything.
Then again, I didn't get to play the beta too much so I'm probably missing something, like an engineering console I haven't seen.