After the storm your system yields less: where is it?

The symptom: after a stormy night or a thunderstorm the app shows lower yield than you are used to, or part of the system reports nothing at all. The weather is back to normal, but the curve does not return to its old level.

Cause one is the dullest and the most common: the inverter tripped a protection and did not come back on its own. Look there first — a fault code or an unlit indicator tells you more than the roof does. Cause two is a shifted panel or a loosened clamp; KNMI speaks of severe gusts from 75 kilometres per hour, and that is enough to pull at the edge of an array. Cause three is new shade: a broken branch that landed on the array, or dirt blown into one spot. Milieu Centraal states that shade on one panel reduces the yield of the whole system in most set-ups — so a single branch explains a loss that looks larger than it is. Cause four is electrical: a tripped protection or cable damage after lightning nearby.

What you can do yourself: read the inverter and note the fault code; compare yield per string or per panel if your app shows it, because one deviating string points the way; and from the ground, scan the row with binoculars for height differences, loose cables and dirt that was not there before. Photograph what you see — it saves the technician a search.

Where it stops is the roof and the installation itself. The Dutch labour authority Arboportaal states that measures against fall risk are legally required above 2.50 metres, and that below that they are still needed where there is a risk of falling. You do not work on the inverter or the DC cabling yourself: it stays live as long as light falls on the panels, even with the switch thrown. A yield check with inspection costs € 85-165 and identifies the cause; repair falls under maintenance and small repairs (€ 95-250). Every rate is in the price index.