I can't work out any sensible reason why one would install solar panels absolutely horizontal. When it rains, water pools on these panels, also condensation most mornings. One end could be a bit higher as other things on the roof are higher, so there is some room height wise without blocking neighbouring views. Another building nearby at least has about 2 degrees slope.
I am at a loss for the "benifits" of rain water pooling on solar panels.
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I had recollections of a minimum slope for roof water runoff. A quick web check and suggested minimum slope is recommended as 3-5 degrees.
We often hear of flat roofs in Australia having a collapse with hailstone loadings.
My old boss with Danish ancestry spoke about roofs in Denmark being built to a code for a certain snow depth.
The photo was a house. Unless the flat roof was seen by anyone, I would not think the aesthetics are that important.
So would it not be more beneficial for the panels to be sloped towards the sunshine?
Also better to have the roof with the necessary slope for proper water runoff of the larger area of the roof sheeting.
My solar panels on my van are notionally flat. Yes, loss of solar efficiency but better and easier for travelling. The panels are relatively small so runoff impedance is negligible.
The hailstone loading that I mentioned before was not the impact loading but the weight loading of the hail that accumulated on relatively flat roofs.
The solar panels on my house roof have been replaced twice, in 2024 and 2026, from hail damage.
The first incident of damage was not visible damage to the eye but thermal imaging revealed hot spot damage which reduced the long term performance of the panels. That hailstone damage was caused by pea to marble sized hailstones at high intensity. Insurance replacement.
The second incident of damage resulted with some of the panels dented and shattered. Similarly, panels on the van were also damaged. Hailstones were 30mmx60mm max size, though not severe intensity. Insurance repair for the house. Self repair for the van.
