Consider a crystalline PV module with the following output parameters mentioned at STC (Standard Test Conditions) conditions by the manufacturer.
Pmax = 300 W
Voc = 40 V
Isc = 8 A
NOCT = 40°C
Temperature coefficient of power = -2 W/°C
If the ambient temperature falls to 15°C while the irradiance is 1000 W/m², what is the cell level temperature in ºC, as per the NOCT model?
a) 40
b) 270
a)Tcell=40 oC
b)Pout=270W
To calculate the cell level temperature as per the NOCT model, we need to use the equation:
Tcell = Tref + NOCT_coeff * (Irradiance - Irradiance_ref)
Where:
Tcell = Cell level temperature (ºC)
Tref = Reference temperature (ºC), which is 25°C
NOCT_coeff = Temperature coefficient of power (°C/W)
Irradiance = Actual irradiance (W/m²)
Irradiance_ref = Reference irradiance (W/m²), which is 1000 W/m²
Given:
NOCT = 40°C
Irradiance = 1000 W/m²
Using the equation, we can calculate the cell level temperature:
Tcell = 25°C + (-2 W/°C) * (1000 W/m² - 1000 W/m²)
Since the actual irradiance is the same as the reference irradiance, the difference is zero, and therefore the term in parentheses becomes zero.
Tcell = 25°C + 0
Tcell = 25°C
Therefore, the cell level temperature in °C, as per the NOCT model, is 25°C.
To calculate the cell level temperature in ºC using the NOCT model, we need to use the following formula:
Tc = Ta + (NOCT - 20) * (Irradiance / 800) + (Pmax / (Isc * Voc)) * (NOCT - 20)
Where:
Tc is the cell level temperature in ºC
Ta is the ambient temperature in ºC
NOCT is the nominal operating cell temperature in ºC
Irradiance is the solar irradiance in W/m²
Pmax is the maximum power output of the PV module in W
Isc is the short-circuit current of the PV module in A
Voc is the open-circuit voltage of the PV module in V
Given that:
Ta = 15°C
NOCT = 40°C
Irradiance = 1000 W/m²
Pmax = 300 W
Isc = 8 A
Voc = 40 V
Using the provided values in the formula:
Tc = 15 + (40 - 20) * (1000 / 800) + (300 / (8 * 40)) * (40 - 20)
Simplifying the equation:
Tc = 15 + 20 * (1.25) + 0.9375 * 20
Tc = 15 + 25 + 18.75
Tc = 58.75 ºC
Therefore, the cell level temperature, as per the NOCT model, is approximately 58.75 ºC.