I recently listened to a residential solar PV presentation. The company proposed installing a 7-kilowatt system at its expense; I would be responsible only for a fixed monthly lease payment under a 20-year contract. The financial model showed savings each year. However, a critical assumption not addressed was that these savings assume that the current residential rate structure does not change over the next 20 years.
If, in fact, at some future time, residential customers were charged for energy and demand separately (the way large companies are charged), then it is very likely that a residential solar customer would pay more for solar (i.e., negative savings). All homeowners considering solar should ask the solar provider a critical question: Are you willing to guarantee that, in any future year, the total price I pay (to the solar provider and to PG&E) will be less than the price I would pay to PG&E if I did not have a solar system? I can tell you that the solar company will not agree to such.
What this means to you is that your savings are far from guaranteed. Solar companies should disclose this reality.