How do solar PV panels stand up to the extremes of rain, wind and hail? What about their resistance to the fury of the typical Highveld thunder storm? It’s a good question, considering the expected lifespan of a solar PV installation is 25 years or more. It’s bound to see a good many storms in its lifetime.
Fortunately, the answer is certain panels – from reputable manufacturers – stand up very well to the rigours of harsh weather. The key is to select panel arrays capable of withstanding Mother Nature’s rage and ferocity at its worst.
Panels featuring tempered glass, for example, are particularly strong and long-lasting while amorphous panels, combining flexible plastic material, are highly resistant to hail damage and any harm that may occur (unlikely) will not substantially affect the array’s performance.
The strength of solar PV panels is measured and rated in a number of ways. The first rating is for static loading – usually applicable to snow loading – which shouldn’t interest us here in sunny South Africa.
What should interest us is the rating for wind loading. Wind is a much more dynamic force and can fluctuate in intensity rather rapidly. This is referred to as mechanical load.
While static and mechanical loading are tested in different ways, the combined force a panel can withstand is measured in Pascals (Pa). The normal test threshold is 2400 Pa, but it’s best to choose a panel capable of passing a mechanical load test of 5400 Pa – particularly if it’s going to be part of an array sited in extremely windy areas, such those found along the eastern Cape coastline.
By far the most impressive test of a solar PV panel is for its hailstone resistance. The Class 4 hailstone test (devised by the Renewable Energy Test Centre in California) subjects solar PV panels to multiple impacts from 50mm diameter hailstones – bigger than golf balls – frozen at minus 17degrees, at terminal velocities of 76 metres per second or a staggering 400-plus km/h. Panels that pass this test represent the very best available.
So, if you are in the market for a rooftop solar PV installation, take out good insurance in the form of a quality solar panel array from a reputable supplier and breathe easy for 25 years or more.