Skip to main content
This stage covers the aggregation of multiple DC fields to a common operating point, DC-applied degradation, and the conversion of DC power into AC power at the terminals. It accounts for inverter operating constraints, temperature derating, and conversion efficiency losses.

​
Models in This Section

​
DC Field Aggregation

Calculates the combined DC input when multiple DC fields with different characteristics connect in parallel to a common inverter. Uses weighted voltage averaging to determine the shared operating voltage, then recalculates each field’s current contribution at that voltage. The resulting power may be less than the sum of individual maximum powers due to mismatch between fields.

​
Degradation Losses (DC Applied)

Applies time-dependent degradation to the aggregated DC power before inverter operating region determination. Supports constant-rate (Linear DC), variable per-year (Non-Linear DC), and supplemental mechanisms. Because degradation is applied before the inverter determines its operating point, it directly affects behavior.

​
Inverter Temperature Derating

Reduces inverter AC capacity based on ambient temperature and site elevation using manufacturer kVA curves. The derated capacity establishes the maximum AC power output for subsequent calculations.

​
Inverter Operating Regions

Classifies inverter state into 12 regions based on DC voltage and power relative to specifications. Determines whether the inverter performs tracking, clipping, voltage adjustment, or shutdown.

​
Inverter Efficiency

Calculates conversion efficiency from manufacturer-supplied curves:
  • Legacy Model (V3-10): Bilinear interpolation with DC power input
  • Sandia Model (V11+): Polynomial curve fitting with AC power output

​
Calculation Sequence

  1. DC Field Aggregation: Combine DC power from multiple fields at common operating voltage
  2. Degradation (DC Applied): Apply time-dependent degradation to aggregated DC power
  3. Temperature Derating: Determine temperature-corrected maximum AC power capacity
  4. Operating Region: Classify inverter state based on DC voltage, power, and temperature-corrected AC power capacity
  5. MPPT/Clipping/Voltage Adjustment/Shutdown: Track maximum power point, limit output to rated capacity, adjust voltage to MPPT window, or shut down
  6. Efficiency: Calculate DC-to-AC conversion efficiency from curves
  7. AC Output: Apply efficiency to determine final AC power