Solar PV Array Sizing Calculator implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t4-150

Effect

Computation or source lookup only

Input and validation requirements

The sizing calculation becomes undefined when peak sun hours are zero because the required panel-count denominator vanishes. The calculator also has a severe unit-convention hazard if a derate entered as 80% is treated as factor 80 rather than 0.80. The discrete ceiling branch causes a one-panel to two-panel jump for an arbitrarily small load increase above an exact boundary.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "panel_power_wp": 400,
    "panel_voc_v": 49.5,
    "panel_isc_a": 10.2,
    "daily_load_wh": 7200,
    "peak_sun_hours_per_day": 5,
    "derate": 0.8,
    "nseries": 10,
    "nparallel": 2
  },
  "expected_outputs": {
    "panel_count": 20,
    "array_power_w": 8000,
    "string_voltage_v": 495,
    "string_current_a": 20.4,
    "daily_energy_wh": 32000,
    "monthly_energy_wh": 960000,
    "monthly_energy_kwh": 960
  },
  "working": "Panel count = 10×2 = 20. Array power = 400×20 = 8,000 W. String voltage = 49.5×10 = 495 V. String current = 10.2×2 = 20.4 A. Daily energy = 8,000×5×0.8 = 40,000×0.8 = 32,000 Wh/day. Monthly energy = 32,000×30 = 960,000 Wh = 960 kWh."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json