10 Module Deployment and Energy Rating
271
10.4.4.4 Failures Caused by Natural and Man-Made Hazards
Natural and man-made hazards (Fig. 10.12b) can again lead to infant, midlife or
wear-out failures. These include: mechanical damages due to hail, heavy snow load,
earthquakes, wind load, typhoons and any kind of natural disasters; thermal damages
due to fire or lightning; corrosion of various components due to salt mist (particularly
relevant in maritime installations), bird drops or atmospheric pollution.
If module qualification and type approval according to the international standard IEC 61215 has been carried out, we can, in principle, have confidence on the
capability of the PV module to withstand at least some of the stresses described in
this section. The standard itself is continuously improving to induce manufacturers
to sell more and more reliable products, which can survive even the most severe
environments.
Detection: by visual inspection.
Prevention: impossible to predict.
10.4.4.5 Failures Caused by Hot Spots
Finally, we should mention hot spots - a concept which has been already introduced in
the previous chapter: it is the overheating of a cell due to partial shading
9 and reverse
bias operation. It often occurs in combination with a bypass diode failure. The bypass
diode is responsible for limiting the effects of partial shading: but while we will see
partial shading as an obvious example of recoverable failures, the effect of a hot
spot is usually unrecoverable. Overheating of a part of the cell can cause burning
and oxidation of busbar connectors, and consequently also of other components
(encapsulant, glass and backsheet) with serious damage to the module. Furthermore,
hot spots can be caused by defects within the module (cracks, shunts, poor solder
joints leading to high series resistance, local delamination, etc.).
Detection: by visual inspection and thermography.
Prevention: avoid partial shading, where possible; check the quality and robustness
of the components.
10.4.5 Partially Recoverable Failure Modes
We come now to three failure modes that we classify as “partially recoverable”
because they lead to a degradation in the efficiency of the solar module, which
can be reversed, although typically without being able to fully restore the original
performance. These failure modes have the following characteristics in common:
9 Hot spots can also be due to shunts inside the cell. A test on hot spot endurance is present in the
international standard for module qualification and type approval, IEC 61215.
271
10.4.4.4 Failures Caused by Natural and Man-Made Hazards
Natural and man-made hazards (Fig. 10.12b) can again lead to infant, midlife or
wear-out failures. These include: mechanical damages due to hail, heavy snow load,
earthquakes, wind load, typhoons and any kind of natural disasters; thermal damages
due to fire or lightning; corrosion of various components due to salt mist (particularly
relevant in maritime installations), bird drops or atmospheric pollution.
If module qualification and type approval according to the international standard IEC 61215 has been carried out, we can, in principle, have confidence on the
capability of the PV module to withstand at least some of the stresses described in
this section. The standard itself is continuously improving to induce manufacturers
to sell more and more reliable products, which can survive even the most severe
environments.
Detection: by visual inspection.
Prevention: impossible to predict.
10.4.4.5 Failures Caused by Hot Spots
Finally, we should mention hot spots - a concept which has been already introduced in
the previous chapter: it is the overheating of a cell due to partial shading
9 and reverse
bias operation. It often occurs in combination with a bypass diode failure. The bypass
diode is responsible for limiting the effects of partial shading: but while we will see
partial shading as an obvious example of recoverable failures, the effect of a hot
spot is usually unrecoverable. Overheating of a part of the cell can cause burning
and oxidation of busbar connectors, and consequently also of other components
(encapsulant, glass and backsheet) with serious damage to the module. Furthermore,
hot spots can be caused by defects within the module (cracks, shunts, poor solder
joints leading to high series resistance, local delamination, etc.).
Detection: by visual inspection and thermography.
Prevention: avoid partial shading, where possible; check the quality and robustness
of the components.
10.4.5 Partially Recoverable Failure Modes
We come now to three failure modes that we classify as “partially recoverable”
because they lead to a degradation in the efficiency of the solar module, which
can be reversed, although typically without being able to fully restore the original
performance. These failure modes have the following characteristics in common:
9 Hot spots can also be due to shunts inside the cell. A test on hot spot endurance is present in the
international standard for module qualification and type approval, IEC 61215.