NOCT › Published

Method

The cell temperature rise above the ambient air is the rise at nominal operating conditions, 800 W/m² at 20 °C ambient, scaled in proportion to the plane irradiance (1). The light the module turns into electricity does not heat it, so the rise is reduced by the module efficiency over the transmittance-absorptance product. The wind term scales the heat loss from its value at 1 m/s to the wind of the timestep. The irradiance is the plane irradiance after shading and soiling, before the glass reflection. The NOCT is the module's rated NOCT. A module without one takes 45 °C, with a notice.

Settings

Setting	Value
Nominal operating cell temperature $T_{NOCT}$	the module's rated NOCT; 45 °C when it has none
Transmittance-absorptance product $\tau\alpha$	0.9

The math

$$T = T_{amb} + \frac{G_T}{800}\,(T_{NOCT} - 20)\left(1 - \frac{\eta_{STC}}{\tau\alpha}\right)\frac{9.5}{5.7 + 3.8\,v} \tag{1}$$

where

Symbol	Meaning	Unit
$T$	the cell temperature	°C
$T_{amb}$	the ambient temperature	°C
$G_T$	the plane irradiance before the glass-reflection step	W/m²
$T_{NOCT}$	the nominal operating cell temperature	°C
$\eta_{STC}$	the module efficiency at standard test conditions	—
$\tau\alpha$	the transmittance-absorptance product	—
$v$	the wind speed	m/s

References

1. Duffie & Beckman, Solar Engineering of Thermal Processes, 4th ed., Wiley 2013

API

thermal.model = noct_published, thermal.transient = false

Symbols follow the symbol registry.