I always come back to this:
The problem isn't the technology, the problem is that the technology isn't sufficiently regulated.
If we have real privacy regulation in the US and the EU (the EU is at least starting to take things seriously but still has a lot of regulation written by lawyers instead of technicians), we might be able to implement this kind of technology without these kind of fears, because there would be severe penalties for using consumer data in such a way.
Because the reality is, spying on consumers isn't the only reason companies are moving to a smart-grid type setup, and it's because it gives them a lot more real-time data about how their grid is functioning and where inefficiencies lie. That's a good thing, and it's just a bonus in their eyes that they can also spy on the energy use habits of their customers.
If we had strict regulation of that kind of data, we might not be in such a position to have to worry about such services, because we could rest easy knowing if they were caught doing such a thing, that their asses would be nailed to the wall.
Of course, that also means we would have to solve certain aspects of corporate governance that allow individuals to avoid going to jail due to "incorporation." No, that shit has to stop, too. We can't let these rich asshats hide behind their corporate coffers for their wrongdoing because you can't put a business in jail. So if a business is a person, give it the damn death penalty and nationalize that shit if they're caught fucking with consumer data.
Anyway, just my two cents. It's not the technology that's the problem, it's how it's used, and how there effectively isn't any legislation and regulation to prevent its abuse.