Good question! Allow me to clarify. When you switch to solar you are effectively trading your power bill for a solar loan. That loan is for the panels and inverters themselves. After you finish paying for the panels, you no longer make a monthly payment.
The "12 months free" means that we pay for the first 12 payments on your system. Furthermore, with the current incentives in the state, you can go up to 9 years without paying for power!