Thermal model

What it is

Selects the formula that computes the module temperature from irradiance, ambient temperature and wind.

Typical values and how to get it

Chosen on the Model tab.

Values

Prilliman transient = prilliman (default): Faiman's heat balance with the module's operating efficiency, then Prilliman's transient weighting for the module's thermal inertia · Faiman = faiman_steady: Faiman's heat balance with the rated efficiency and no thermal lag · NOCT (Duffie and Beckman) = noct: the temperature rise at nominal operating conditions (800 W/m², 20 °C ambient) scaled by irradiance and wind, with a NOCT of 45 °C, or 49 °C on rooftop racking · NOCT, module's rated NOCT = noct_module: the NOCT model with the module's rated NOCT from its CEC entry plus a standoff adjustment for the mounting gap; 45 °C when the module has no rated NOCT · SAPM (King 2004) = sapm: King's Sandia model: the module back temperature from irradiance, wind and two coefficients, plus a conduction step to the cells; the coefficients come from King's table by racking and module unless given · Fuentes = fuentes: Fuentes's heat balance with the module's heat capacity carried from one timestep to the next (the PVWatts version 5 implementation); the installed NOCT is 45 °C, or 49 °C on rooftop racking

References

1. Faiman 2008, Assessing the outdoor operating temperature of photovoltaic modules, Progress in Photovoltaics 16(4) 307–315
2. Prilliman, Stein, Riley & Tamizhmani 2020, Transient weighted moving-average model of photovoltaic module back-surface temperature, IEEE Journal of Photovoltaics 10(4) 1053–1060
3. Duffie & Beckman, Solar Engineering of Thermal Processes, 4th ed., Wiley 2013

API

thermal.model