Temperature Coefficient Testing for Solar Modules
Perform Temperature Coefficient Testing on solar modules at our Accredited PV Laboratory.
What is the Temperature Coefficient test?
The measurement of Temperature Coefficients of solar modules are performance parameters intended to determine the temperature coefficients of maximum power, short-circuit current and open circuit voltage from module measurements. Temperature coefficients are often used by end users to calculate the expected energy yield of the modules in hot climate locations intended for installing the solar modules. They are valid at 1000 W/m2 level of irradiance that is used in the lab, unless the linearity of the solar module at different levels of irradiance has been proven.
Why is the Temperature Coefficient of solar modules important?
Crystalline solar cells are the main cell technology used widely, and usually come with a temperature coefficient for the maximum output power (Pmax) of about -0.5% / degree Celsius.
The rated power as generally indicated on the module’s label is measured at STC conditions which means a temperature of 25 degrees Celsius, and with any temperature increase above 25°C you have to take into account power losses of 1% for every 2°C increase.
Most installed solar modules in sunny countries easily reach higher temperatures that are much higher than the standard temperature of 25°C. In fact, temperatures of 50°C and above can be easily reached.
Solar module testing and Temperature Coefficients
Each solar module has its own Temperature Coefficient. During this measurement, the temperature coefficients of current (α), voltage (β) and peak power (δ) are determined.
For this test, the following equipment setup is needed:
- a radiant source (usually solar simulator)
- equipment to vary the temperature of the solar module
- accurate temperature monitoring
- equipment to measure the voltage and current of the solar module
The resulting coefficients are applicable at the same irradiance level at which the measurement was made.
Temperature Coefficient Testing and IEC 61215
The Temperature Coefficient Test is one of the main qualifying tests carried out on PV modules in order to qualify them for IEC 61215 certification.The Temperature Coefficient test is carried out after initial wet leakage current test and before the NOCT test.
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