In reality, what is happening is that because of "alternative" sources of energy, electricity is plentiful during the day, and scarce during the evening. Also, only turbines (hydro/thermo power plants) can be adjusted to keep current and voltage in the network constant, so we still need them, but because of the "green" sources, they are becoming less profitable for the operators.
TL;DR: alternative energy sources cause us to have too much electricity during the day and too little during the evening, both of which is costing us money.
If you produce energy, you get paid for it, but also pay a levy depending on how well your supply fits the demand. The levy goes to whoever fills in the gaps.
For example, the PJM interconnection holds an annual capacity auction. This essentially pays for the capital costs of keeping gas turbines around, at idle. The cost of actually running the turbines is covered by a separate daily auction for actual electricity production.
So when PV prices fall to the bottom (trends indicate they will), electricity prices produced by PV will fall as well. Coal/Nuclear/etc will become unviable. What do we do then? Electricity will be basically free then.