Solar PV Cell Temperature (NOCT) & Hot-Weather Power Derating Calculator

Calculate solar cell temperature (°C) and hot-weather wattage loss above 25°C STC.

Derated Real-World Array Output
8.19 kW
Operating PV Cell Temperature (T_cell) 65.69 °C
Thermal Derating Loss Above 25°C 13.83 %
Irradiance-Adjusted Pre-Thermal Power 9.5 kW
Inputs
⚡ Scenarios:
kW
Array nameplate rating at 25 °C Standard Test Conditions (kW).
°C
Outdoor ambient air temperature in °C.
W/m²
Incident solar irradiance G in W/m².
°C
Nominal Operating Cell Temperature (NOCT, typically 43–47 °C).
%/°C
Power temperature coefficient γ (typically −0.29%/°C to −0.38%/°C).
Results & Graph
Derated Real-World Array Output
8.19 kW
Operating PV Cell Temperature (T_cell)
65.69 °C
Thermal Derating Loss Above 25°C
13.83 %
Irradiance-Adjusted Pre-Thermal Power
9.5 kW

Derated Real-World Array Output

Graph 1 • Solar PV Temp Derating • Domain Architecture & Live Telemetry Maps Array Stc Rated Kw, Ambient Air Temp Celsius, Solar Irradiance Wm2 through Solar PV Temp Derating Formula.
Solar PV Temp Derating • Generation → Conversion → Storage Bus 1. SOURCE / ARRAY 10 kW Array Stc Rated Kw 2. DELIVERED RATING 8.19 kW Derated Real-World Array 3. SECONDARY OUTPUT 65.69 °C Operating PV Cell Temper
Graph 2 • Derated Real-World Array Output Across Array Stc Rated Kw Sweep (40% → 160%) Evaluates T_cell = T_amb + ((NOCT − 20) / 800) × G; P_actual = P_STC × (G / 1000 across 7 operating points (current input highlighted).
0 kW 7.21 kW 14.41 kW 3.27 4kW 4.91 6kW 6.55 8kW 8.19 10kW 9.82 12kW 11.46 14kW 13.10 16kW
Graph 3 • Joint Sensitivity: Array Stc Rated Kw × Ambient Air Temp Celsius Compares Derated Real-World Array Output when Ambient Air Temp Celsius is shifted +25% (solid) vs. −25% (dashed).
0 kW 6.06 kW 12.12 kW --- Ambient Air Temp Celsius @ 75% 5.53 -30% 6.71 -15% 7.90 +0% 9.08 +15% 10.26 +30%
Summary: At 36°C ambient and 950 W/m², solar cell temperature reaches 65.7°C (+40.7°C above STC), causing a 13.83% thermal power loss and delivering 8.19 kW.
Summary: At 36°C ambient and 950 W/m², solar cell temperature reaches 65.7°C (+40.7°C above STC), causing a 13.83% thermal power loss and delivering 8.19 kW.
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Formula & Mathematical Methodology: Solar PV Temp Derating Formula

Tcell = Tamb + ((NOCT − 20) / 800) × G
Pactual = PSTC × (G / 1000) × [1 + (γPmp / 100) × (Tcell − 25)]
T_cell = T_amb + ((NOCT − 20) / 800) × G; P_actual = P_STC × (G / 1000) × [1 + (γ_Pmp / 100) × (T_cell − 25)]
  • arrayStcRatedKw: Array Stc Rated Kw (kW)
  • ambientAirTempCelsius: Ambient Air Temp Celsius (°C)
  • solarIrradianceWm2: Solar Irradiance Wm2 (W/m²)
  • noctRatingCelsius: Noct Rating Celsius (°C)
  • tempCoeffGammaPctPerC: Temp Coeff Gamma Pct Per C (%/°C)

Rounding: Engineering outputs round to 2–3 decimal places; discrete material bag/unit counts round up via ceiling.

Worked Example: Engineering Scenario: Solar PV Temp Derating

Calculate solar cell temperature (°C) and hot-weather wattage loss above 25°C STC.

  1. Enter your system dimensions, electrical/RF ratings, or environmental conditions.
  2. Evaluate the governing equation: T_cell = T_amb + ((NOCT − 20) / 800) × G; P_actual = P_STC × (G / 1000) × [1 + (γ_Pmp / 100) × (T_cell − 25)].
  3. Inspect the primary design output, supporting allowances, and 3 SVG schematics.
Result: Computes Solar PV Temp Derating via T_cell = T_amb + ((NOCT − 20) / 800) × G; P_actual = P_STC × (G / 1000) × [1 + (γ_Pmp / 100) × (T_cell − 25)].

Frequently Asked Questions

How does the Solar PV Cell Temperature (NOCT) & Hot-Weather Power Derating Calculator calculate results?

It evaluates T_cell = T_amb + ((NOCT − 20) / 800) × G; P_actual = P_STC × (G / 1000) × [1 + (γ_Pmp / 100) × (T_cell − 25)] directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a required dimension or rating?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Does this engineering calculator work offline?

Yes. All calculations run 100% locally in your browser and work offline via the CalculatorGraph PWA.

Science & Engineering · Renewable Energy & Battery Engineering

Solar PV Cell Temperature (NOCT) & Hot-Weather Power Derating Calculator: inputs, method, and how to read the result

Calculate solar cell temperature (°C) and hot-weather wattage loss above 25°C STC.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Array Stc Rated Kw: Array nameplate rating at 25 °C Standard Test Conditions (kW).
  • Ambient Air Temp Celsius: Outdoor ambient air temperature in °C.
  • Solar Irradiance Wm2: Incident solar irradiance G in W/m².
  • Noct Rating Celsius: Nominal Operating Cell Temperature (NOCT, typically 43–47 °C).

What the calculation includes

With the default values shown, Derated Real-World Array Output is 8.19 kW. The calculation follows Solar PV Temp Derating Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Array Stc Rated Kw from 10 kW to 11 kW changes Derated Real-World Array Output from 8.19 kW to 9 kW. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard NREL, IEEE, ASHRAE, and IRC design equations.
  • Verify final structural, electrical, and mechanical specifications against local building codes.

Scope: Global Engineering & Building Code Standard Check the assumptions and limitations against your situation before relying on the estimate.

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