How to protect photovoltaic panels from hail?

Effects and limitations of hail tests on photovoltaic modules

As part of the certification process, photovoltaic modules are tested in accredited laboratories according to IEC 61215 and IEC 61730.
In particular, one of the tests that the modules undergo is the hail test (IEC61215-2). In this test, a hailstone with a diameter of 25 mm is 'shot' perpendicular to the surface of the module at a speed of 23 m/s at a distance of up to one metre from the surface.
The main objective of this test is to check the integrity of the module after impact with a rigid body, and secondly to assess any possible reduction in performance that could result from broken or damaged cells in the impact area.
Commercially, it is also possible to find modules tested under extreme conditions, such as a diameter of 45 mm and a speed of 30.7 m/s, but these are still laboratory tests.

In any case, it is good to remember two fundamental aspects.
 

• These tests are designed to verify and simulate the behaviour of a module sample under precise conditions and within a laboratory, but this does not mean that modules can be guaranteed against damage caused by natural phenomena such as hail. No manufacturer can claim that its module is hail-proof just because it has passed laboratory tests. This is because it is impossible to estimate the exact size, speed and angle of impact of each individual hailstone during a storm. What can be guaranteed is that the modules on the market have been tested under specific conditions and have achieved positive results.
• Even if a module is visually undamaged after a severe hailstorm, this does not automatically guarantee that it will function as it did before the weather event. It is possible that internal cracks may have formed in the cells, invisible to the naked eye, which could lead to a reduction in the energy produced.
   

In the face of extremely violent hailstorms, such as those that occurred in Veneto and Lombardy in 2023, it is clear that there are no solutions that can completely eliminate the risk. However, it is possible to significantly reduce the possibility of damage through certain preventive strategies:

• Adjusting the angle of the panels: this is not a definitive solution, but it can reduce the risk of damage and can be considered before the photovoltaic system is installed. During installation, it is crucial to choose the best angle for the photovoltaic modules, both to optimise energy collection and to protect them from hail damage. For example, installing the modules in a non-horizontal position can reduce the impact force of each hailstone, helping to minimise potential damage.  In the case of ground-mounted installations or where trackers are provided, this problem can be mitigated by changing the tilt of individual panels. Unfortunately, this is not feasible for an industrial or, worse still, a domestic installation.

• Use high quality photovoltaic panels: Trienergia modules manufactured using MWT Backcontact photovoltaic cells can reduce the likelihood of cells breaking as a result of these impacts. As the individual cells have not been subjected to thermal stress during normal soldering processes during production, they have a higher mechanical strength. In addition, the modules produced by Trienergia use 3.2 mm thick thermally toughened glass, which guarantees good resistance to mechanical stress. Although the trend in the industry is to reduce the thickness of the glass in order to reduce production costs, Trienergia has chosen to use a glass of proven thickness that has been used by many manufacturers worldwide for more than 10 years.

• Insuring the system: the only real and concrete solution, even if it does not prevent damage, is to take out an adequate insurance policy, which can make a decisive contribution to reducing economic losses by ensuring that it expressly covers hail damage.

It is essential to recognise that it is impossible to have zero risk in the face of hailstorms of exceptional intensity. However, by adopting some preventive strategies, the resilience of PV systems can be greatly increased, protecting the investment and ensuring business continuity.

To find out more about photovoltaic panels and the revolutionary MWT Backcontact technology offered by Trienergia, do not hesitate to contact us!