As we all know, the smooth performance of a solar PV module is strongly geared to the factor temperature. Higher than standard conditions temperatures can actually mean losses in maximum output power. Therefore, Eco Green Energy usually aims at optimally cooling the modules. Here, we would like to have a basic introduction to the temperature coefficient of a solar PV module.
What is the temperature coefficient of a PV module?
The temperature of the solar PV module has a direct effect on its ability to generate electricity. This impact is reflected through the temperature coefficient, which is expressed as the percentage decrease in output for every 1-degree Celsius (°C) increase in temperature from 25°C. Solar PV modules are tested for their efficiency at 25°C, which is the cell temperature of Standard Test Conditions (STC). And with any temperature increase above 25°C must consider power losses of 1% for every 2°C increase.
(Source: Eco Green Energy Helios Plus 440-455W datasheet)
Most solar PV modules have a temperature coefficient of around -0.3% / °C to -0.5% / °C. For example, Eco Green Energy’s Helios Plus 450W panels have a temperature coefficient of -0.35% / °C.
(Eco Green Energy Helios Plus 440-455W panels temperature characteristics)
How to calculate the temperature coefficient?
We will take here a solar PV module of Eco Green Energy as an example, and calculate the power loss when this type of solar module is installed in a region with an ambient temperature of 28℃ using Typical Rack-Type installation (temperature of panels will be 30℃).
We pick Helios Plus 144 cells module: the 450W. The temperature coefficient of the maximum output power (Pmax) at NMOT (Nominal Module Operating Temperature) is -0.35%/°C.
Now, let’s have a look at this example, with the solar module reaching 58°C (28℃+30℃), the power loss of this module is:
l 58°C – 25°C = 33°C, which is the temperature difference between the module’s Pmax at NMOT and the hypothetical example temperature of 58°C reached by the cells
l 33°C x -0.35% = -11.55%, which means that the module loses 11.55% in the power output when the cells reach 58°C
Solar module power loss: -11.55% x 450W = -51.98W. The maximum power this module will operate at 58°C is 398.02W.
Then, we can make a comparison with two different panels with different temperature coefficients to see how a small tolerance led to a big difference.
– Power differences generate between Helios Plus and B Panels is approx. 6W.
– 6W *10 panels * 4h (Average working systems hours per day) * 365 days = 87.6 kWh
Does it Matter for Your Solar Project?
A solar panel’s temperature coefficient is not the only factor that influences a panel’s overall power output. Yet, it is a good starting point for calculating a more realistic level of production for your specific setup.
Then, when you are choosing the best solar panels for your systems, you can think of how hot your panel may get. And you can use that to estimate how efficient they will be on your rooftop or other locations.
(Eco Green Energy Cambodia solar water pumping system using Helios Plus 450W panels)
Take a recent project in Cambodia as an example, as we can see, the climate in Cambodia is tropical, hot all year round, with a temperature range of 22℃ to 35℃. Eco Green Energy Helios Plus 450W panels perfectly match the solar water pumping system under these special weather conditions.
(Source: World Climate Guide)