Capacity-based cost, incentive, and revenue treatment for PV

[cpaulgilman]

Background

SAM calculates the capacity-based incentive (CBI) based on:

• DC nameplate capacity for PV in kWdc
• AC maximum discharge power for battery in kWac
• AC nameplate capacity for all other technologies in kWac

Capacity based O&M cost is based on:

• DC nameplate capacity for PV in kWdc, except for hybrids where it is in kWac
• AC storage capacity for battery in kWhac
• AC nameplate capacity for all other technologies in kWac

Major equipment replacement reserves:

• DC nameplate capacity for PV in kWdc, except for hybrids where it is in kWac
• AC nameplate capacity for all other technologies in kWac

Capacity payments for revenue:

• DC nameplate capacity for PV in kWdc, except for hybrids where it is in kWac
• AC nameplate capacity for all other technologies in kWac

This is based on the industry convention of defining PV nameplate capacity as DC capacity of the array, and works fine for systems with PV as the only power generation equipment. For hybrids, it results in mixing DC and AC capacities in CBI and operating cost calculations.

Note that the total hybrid system nameplate capacity is the total generation capacity, which is the sum of AC capacities for all subsystems, including PV, and does not include battery discharge power.

Proposed Changes

For all configurations with PVWatts, Flat Plate PV or High-X Concentrating PV:

1. Use PV AC capacity (inverter capacity) as basis for:
   a) CBI
   b) Capacity-based operating cost calculations
   c) Replacement reserve accounts
   d) Revenue capacity payments
2. Show PV AC capacity factor Metrics table.

Considerations

• PV models calculate an AC and DC capacity factor. DC capacity factor is reported in Metrics table, AC is available in Data Tables.
• Industry typically defines PV system nameplate capacity in DC kW.
• Use approach consistent with NREL ATB and NREL and LBL PV annual market reports.