Photovoltaic thermography: what is it for, costs, how it works and all useful information aboutthermographic analysis of a photovoltaic system.
We have already explained to you what is thermography and what are its applications in green building and in the renewable energy sector, today we deepen in detail how it functions and what it is forphotovoltaic thermography.
Usually, the holder of a photovoltaic systembegins to wonder about thetemographywhen it suspects a failure so much that its installation causes a drop in production; to get a 360 ° overview of the reasons that could lead to a drop in the electricity production of a photovoltaic system, we invite you to read our papers:
Photovoltaic system that does not produce, what to do?
Why does the photovoltaic system produce less energy?
Since thephotovoltaic thermographyit is an analysis that has a certain cost, we recommend that you first exclude all the other causes that could have led to a drop in system performance and, if no errors arise, finally proceed withthermography. The costs of the photovoltaic thermography depend on whether there is a guarantee or a maintenance plan stipulated at the time of purchasing the photovoltaic modules, the prices also depend on the difficulty in accessing the system as in the case of photovoltaic roofs and the size of the system. A fluctuation in costs can be seen between the different companies and especially between the different regions of Italy.
Therethermographyinfrared is important to ensure goodmaintenance of the photovoltaic system. Therephotovoltaic thermographyit is not only able to return reports for the verification and repair of modules affected by an alleged failure, through thethermographic analysis of photovoltaicsit is possible to obtain a historical view of the evolution of localized defects so as to directly identify the root cause and avoid future similar failures.
The nominal working temperature of a photovoltaic cell, called NOCT (acronym for Nominal Operating cell Temperature), is the average equilibrium temperature of a cell inside a module placed in particular environmental conditions (irradiation: 800 W / m2, temperature environment: 20 ° C, wind speed: 1 m / s) and electrically in open circuit, installed on a frame with optimal exposure in order to ensure that at noon the sun's rays affect the entire exposed surface.
The NOCT is a parameter provided by the manufacturer, it is typically equal to 40-50 ° C, but it can reach 60 ° C for double-glazed modules. It is important to know that all photovoltaic panels decrease their performance as the operating temperature increases.
Many analyzes have shown that photovoltaic systems work best at a temperature of 25 ° C. Higher temperatures significantly reduce the performance of the photovoltaic system, due to the overheating of the photovoltaic modules. Each manufacturer enters in the technical data sheet the temperature coefficient through which it indicates the loss of performance for each additional degree of temperature.
If one or more photovoltaic cells are excessively overheated, they will cause a drop in production which can also have a negative impact on the cells or even on adjacent panels.
Thanks to the thermographic analyzes it is possible to detect the Photovoltaic cells which present the so-called "hot spots". The difference in temperature cannot be observed with the naked eye, so the instrumental intervention of a thermal imager is required in order to produce a thermography capable of highlighting "hot spots" and acting promptly to stem the damage (with the creation of suitable bypasses that isolate the "dead cells") or solve it (by replacing the faulty modules).