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DC-AC Conversion models calculate the transformation of DC power from connected DC fields into AC power output at the inverter terminals. This stage accounts for the aggregation of multiple DC fields, inverter operating constraints, temperature derating, and conversion efficiency losses.

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Models in This Section

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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.

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DC Field Aggregation

Calculates the combined DC input when multiple DC fields with different I-V 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.

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Inverter Operating Regions

Classifies inverter state into 13 regions based on DC voltage and power relative to specifications. Determines whether the inverter performs MPPT tracking, clipping, voltage adjustment, or shutdown.

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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

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Calculation Sequence

  1. Temperature Derating: Determine temperature-corrected maximum AC power capacity
  2. DC Field Aggregation: Combine DC power from multiple fields at common operating voltage
  3. Operating Region: Classify inverter state based on DC voltage and power
  4. MPPT/Clipping: Track maximum power point or limit output to rated capacity
  5. Efficiency: Calculate DC-to-AC conversion efficiency from curves
  6. AC Output: Apply efficiency to determine final AC power