THERMOGRAPHY AND PHOTOVOLTAIC
The inspection of the efficiency of photovoltaic panels must be in accordance with the standards IEC61215 and IEC61646 and thermography is one of the tools mentioned in the rules for running it.
Our company makes thermographic investigations of photovoltaic systems: thermography is the most effective method for testing a photovoltaic module.
Thermography can be used to:
– Identify, during normal solar load, defective cells with temperatures above the maximum working temperature (normally 85 ° C).
– Identify defects in the connections between cells and diodes.
– Evaluate losses of efficiencies of panels with non-uniform distribution of temperatures due to cells or groups of cells with higher temperature than normal.
If a cell does not generate energy is because it is exposed to solar radiation or is defective.
A defective cell normally takes energy from other cells and can become excessively hot. The cell efficiency depends on many factors such as solar load, dirt, temperature, quality, etc.. The cells of the panels can be inspected, when exposed to solar radiation, both front and from the back.
This means a decrease of efficiency of the cells, normally equal to 0.5% / ° C, for the cells to crystalline silicon. A single defective cell in a module produces a reduction of efficiency much higher than the extent of the problem of single cell, since the cells are connected in series. Finally, a module with a damaged cell, in addition to producing a reduction in the efficiency of the string of modules in series, causes a problem of mismatch of the strings in parallel, and a small problem translates in great damage
The image below shows a panel with a defective cell and a whole string with probable connection problem:
The image below shows a picture with a fan clogged inverter: