When a home or business has a PV system installed, there is a meter installed (PV meter) on the PV system to track the system’s energy generation (output) in kilowatt hours (kWh). At the same time, CPS Energy replaces the existing building meter which tracks energy supplied to the home or business with a new dual-read billing meter (net meter). This dual-read meter captures two different readings:
- the amount of energy supplied to the building by the CPS Energy distribution grid
- any excess energy generated by the solar PV system that was not used by the building at the time it was generated
This excess energy goes back into the CPS Energy distribution grid and is termed “push back”. This energy is “credited” to the customer’s bill just as if the building had directly used it.
See Solar Power & CPS Energy: How It Works
CPS Energy billing and reconciliation of energy used (“true up”) happens on a monthly billing cycle. The CPS Energy meter is read for the amount of energy supplied to the building by the CPS Energy distribution grid and any excess “push back” energy fed back to the grid.
The customer’s bill is based on:
Amount of Energy Supplied by CPS Energy minus Amount of Energy Fed Back to the Grid by the solar PV system in kWh.
Because the bill is based on kWhs, the amount of energy fed back into the grid (push back) is credited at the full retail rate.
Note: The customer’s bill does not show the total amount of energy consumed by the building because it does not show the energy generated by the solar PV system that was directly used by the building.
Typically, most systems are sized so that they meet a portion (10% - 50%) of the building’s energy needs. So, even though there may be times when the solar PV system is producing more energy than the building is using (push back), it would be unlikely for the solar PV system to produce more energy than the building consumed over a month’s time.
In the unlikely event that a solar PV system generated more energy than the building used in a month, the excess generation is credited back to the account. But this credit amount would be calculated by multiplying the excess energy generated (kWhs) by what we call our “avoided cost”. The avoided cost amount varies by season and will be between $0.015 and $0.025.