Well, unless specified, I'm going to assume they might still be a reward, though the uses for it may be much less frequent (as it stands, the only missions which need a power regulator and don't provide one - that I know of - are in post-Thargoid recovery systems, and otherwise it's for turning on sites without a mission, I guess?).
But the upgrade requirements are 10 regulators from level 3 to 4 and 15 from 4 to 5, if memory serves. Or, I suppose, were. It was a bit excessive anyway, especially when trying to view it from a realistic standpoint... those things are used for proper fusion reactors, and you have to provide dozens of them just to get a suit upgraded? Pf. Yeah, right...
But the upgrade requirements are 10 regulators from level 3 to 4 and 15 from 4 to 5, if memory serves. Or, I suppose, were. It was a bit excessive anyway, especially when trying to view it from a realistic standpoint... those things are used for proper fusion reactors, and you have to provide dozens of them just to get a suit upgraded? Pf. Yeah, right...