What the storm season does to your panels

Solar panels are usually judged on yield. Structurally they are something else: a series of flat plates hanging off the roof on brackets, with space underneath. That is where wind takes hold.

Dutch meteorological institute KNMI notes that the storm season begins in September and that the first storm often arrives in November. What arrives then is not mainly hourly averages but outliers: from 75 kilometres per hour KNMI speaks of severe gusts, and gusts over 100 kilometres per hour are very severe. Such a gust finds the edge of the array and the fixing that already gives a little.

What you can assess from the ground is more than you would expect. Look along the row with binoculars: do the panels sit in a straight line, or does one stand slightly proud? Is there new dirt or grit on top that was not there before? Are cables hanging loose under the array that used to be tucked away? And after a storm look at the ground too: a fragment of a clamp or a piece of bird mesh in the garden is a clue.

What you do not do is go up to look yourself. The Dutch labour authority Arboportaal states that measures against fall risk are legally required above 2.50 metres, and that below 2.50 metres measures are still needed where there is a risk of falling — and an array makes a roof slippery and hard to read. If you doubt the mounting, have a yield check with inspection (€ 85-165) done; if something is loose, that falls under maintenance and small repairs (€ 95-250). Every rate is in the price index.