Photovoltaic

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Photovoltaic

STC Conditions

Standard Test Conditions (STC) of irradiance and temperature in the solar cell used to characterize cells, modules, and solar generation systems, defined as follows:

· Solar irradiance, 1000 W/m²

· Spectral distribution, AM 1.5G

· Cell temperature, 25 ºC


NOCT conditions

Nominal operating cell temperature in ºC, defined as the temperature reached by the solar cells under the following conditions:

· Solar irradiance, 800 W/m²

· Spectral distribution, AM 1.5G

· Ambient temperature, 20 ºC

· NOCT: Nominal operating cell temperature, ºC


BNPI Bifacial factor

An irradiance is estimated:

\[ G_{BNPI} = 1000\ W/m^2 + \varphi \cdot 135\ W/m^2 \]

· GSTC: Solar irradiance in standard conditions, 1000 W/m²

· GBNPI: Irradiance with bifacial factor, W/m²

· φ: Bifacial factor, %

· Bifacial gain: 100 · (GBNPI/GSTC - 1), %


Solar cell temperature

\[ T = T_{\text{o}} + \frac{G}{G_{\text{NOCT}}} · (T_{\text{NOCT}} - 20ºC) \]

· T: Cell temperature, ºC

· To: Ambient temperature, ºC

· G: Solar irradiance, W/m²

· GNOCT: Solar irradiance, 800 W/m²

· TNOCT: Nominal operating cell temperature, ºC


Photovoltaic module power \[ P = P_{\text{MAX}} · \frac{G}{G_{\text{STC}}} \cdot (1 + \frac{\gamma}{100} \cdot (T - T_{\text{STC}})) \]

· Pmax: Peak power of the photovoltaic module, Wp

· G: Solar irradiance, W/m²

· GSTC: Solar irradiance in standard conditions, 1000 W/m²

· γPmax: Coefficient of power variation with temperature, %/ºC

· T: Module cell temperature, ºC

· TSTC: Cell temperature under standard test conditions, ºC


Photovoltaic module curret \[ I = \frac{G}{G_{\text{STC}}} \cdot (I_{\text{STC}} + I_{\text{SC}} · \frac{\alpha}{100} \cdot (T - T_{\text{STC}})) \]

· I: Module current, A

· ISTC: Current under standard test conditions, A

· ISC: Short-circuit current, A

· G: Solar irradiance, W/m²

· GSTC: Solar irradiance in standard conditions, 1000 W/m²

· αISC: Coefficient of current variation with temperature, %/ºC

· T: Module cell temperature, ºC

· TSTC: Cell temperature under standard test conditions, ºC


Photovoltaic module voltage \[ V = V_{\text{STC}} + V_{\text{OC}} \cdot \frac{\beta}{100} \cdot (T - T_{\text{STC}}) \]

· V: Module voltage, V

· VSTC: Voltage under standard test conditions, V

· VOC: Open-circuit voltage, V

· G: Solar irradiance, W/m²

· βVOC: Coefficient of voltage variation with temperature, %/ºC

· T: Module cell temperature, ºC

· TSTC: Cell temperature under standard test conditions, ºC


Maximum system voltage \[ V_{\text{MAX}} = V_{\text{OC}} \cdot (1 + \frac{\beta}{100} \cdot (T_{\text{MIN}} - T_{\text{STC}})) \]

· VMAX: Maximum system voltage, V

· Voc: Open-circuit voltage, V

· βVOC: Coefficient of voltage variation with temperature, %/ºC

· Tmin: Minimum cell temperature, ºC

· TSTC: Cell temperature under standard test conditions, ºC