It’s true that solar energy in the form of wavelengths incident on a PV modules gets converted to electrical energy. For this purpose the PV modules have to be well exposed to the suns rays for optimum results. This makes the solar cells of the modules get over heated and the capacity or the conversion rate can be drastically reduced. Beyond certain critical temperature the cells are liable to be permanently damaged.
What is the operating temperature recommended?
All PV modules are rated considering the operation at particular temperature conditions. A solar cell temperature of 25 0 C is a standard temperature for ratings and the operating temperature known as Nominal Operation Cell Temperature ( NOCT ) is 48 0 C with a tolerance of +/- 2 0 C.
How high the Temperature can rise with no ill effects?
In the case of Mono Crystalline PV panels the manufacturers recommend and guarantee a temperature tolerance up to 85 0 C. The lowest temperature is also specified by them for safe operation which is typically – 40 0 C.
Effects of High temperatures on PV modules
The conversion rate will be reduced in PV modules due to getting over heated. The rate of reduction may vary depending on the quality of the solar cells. Generally manufacturers make these available in graphical form for easy visual interpretation.
The typical graph considers a solar energy of 1000w/m 2 incident on the panels for the purpose of these performance curves. The representation show current ( A ) vs Voltage ( V ) vs. out put electrical power ( w ). A typical characteristic curve of a mass produced Mono Crystalline PV Module show a flat closed circuit current over a voltage range of 0 to 40 Volts.
Beyond the 40 Volts limit there is a steep drop of out put power, voltage and current. At around 50 Volts the out put is nil when the cell temperature is 25 0 C. The curve profile will remain same for different cell temperatures but the out puts may vary accordingly.
Ways to avoid high temperature
The current practice is to ensure enough wind play to carry away the heat built up in the PV modules. This has to be done by careful design of your method of module installations. An array of PV modules could easily interfere with the wind play around each other. Therefore the installer should be extra careful in this type of situation.
Thanks the Techstore Team