A coefficient expressing the relation between a change in a physical property and the change in temperature that causes it.
Solar Panels have negative temperature coefficients which means that when the temperature rises and solar panels heat up, the power output of the solar panel decreases.
The rated capacity, or power, of a solar panel (e.g. 250 Wp) is measured at 25°C. The effect of temperature on the solar panel’s power is measured by its thermal coefficient, expressed as %/K or %/°C. It denotes the % change in power for 1 degree change in Kelvin or Celsius (both are the same on a unit level) above 25°C. A negative (-) sign indicates the direction of the change.
A temperature coefficient of -0.447% indicates that every 1°C increase in temperature over 25°C will cause a 0.447% decrease in power. Equally, every 1°C decrease in temperature over 25°C will cause a 0.447% increase in power.
For those installing solar panels in hot climates (which will be a significant portion of all installations worldwide), it is thus important for you to choose solar panels that have a lower (absolute) temperature coefficient so that the output loss with increase in temperature is minimized.
Source: Solar Panel Temperature Coefficient from Solar Mango’s Solar Dictionary
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Can you give a practical example of what happens and how this will affect the roof top installations. This is the main area where the temperature co-efficient is going to play a major role and unfortunately this is not understood by many installers.
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