[castratikron]

In that sense it's an investment. Your savings are determined by the price of energy, so there's no guarantee the price will stay the same (or increase) over 10 years.

It isn't just the utility's price that can change. There can also be changes to laws regarding net metering. In fact there's loads of cases where local/municipal/state utilities will try to change the law and eliminate net metering so that they don't have to pay for residential solar.

I really think there needs to be some kind of state owned grid where market forces determine the cost of energy. Everyone who wants to hop on the grid gets a meter installed and there would be a marketplace where people would be free to pick where their energy comes from. In that way the cost of energy becomes democratized and takes power away from entrenched utilities that have every incentive to keep them in control of the energy supply and to keep the price of that energy high.