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What is STC ,NOCT, Temperature coefficient? How are they related?

Release:2017/06/02 Company News

STC: 1000W/m2 irradiance, 25°C cell temperature, AM1.5g spectrum according to EN 60904-3.

 

NOCT (Nominal operating cell temperature): Cell temperature under below circumstance, open-circuit module operation temperature at 800W/m2 irradiance, 20°C ambient temperature, 1m/s wind speed.

 

Temperature coefficient of Pmax: connection between power output and cell temperature based on STC 25°C cell temperature criterion.

 

Example:
Taipo 260W solar module Power Output under STC and NOCT

Item No.
TP-265P-60
TP-265P-60
STC
NOCT
Max Power(Pmax)
260W
189.7W
Max Power Voltage(Vmp)
30.3V
27.6V
Max Power Current(Imp)
8.59A
6.87A
Open Circuit Voltage(Voc)
37.7V
34.8V
Short Circuit Current (Isc)
9.09A
7.35A
Nominal operating cell temperature (NOCT)
46 +/- 2°C
Temperature coefficient of Pmax
-0.42%/°C

 

How we get Pmax of NOCT with Pmax of STC, NOCT and Temperature coefficient of Pmax

 

Step 1: We calculate the Pmax under NOCT as per connection between Pmax under STC and Temperature coefficient of Pmax on the assumption that under same 1000W/m2 irradiance.

Pmax of STC * (NOCT-25°) * Temperature coefficient of Pmax

= 260W*[100%+(46°C-25°C)* -0.42%/°C]

=237.068W

 

Step 2: We calculate the Pmax under NOCT 800W/m2 irradiance.

237.068W*(800/100)=189.6544≈189.7W

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