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Sun Shields mutual shadings

In terms of mutual shadings calculation, sun-shields are treated in a similar way as sheds (see Shed Mutual Shadings).

Nevertheless, the user should be aware that sun-shields are inherently un-efficient:

  • At best, only half the total diffuse irradiance can reach the collectors due to the building wall. In regions with a high diffuse fraction (above 45° latitude, it usually represents more than 50%), this leads to significant losses.
  • In low latitudes region, where the sun's height is high during the day, an important fraction of the direct irradiance is blocked by the upper sun-shield.
  • For installation not facing exactly south (or north in southern hemisphere), there is an important direct irradiance shading on the morning or evening. This effect can be seen with the "Shading graph" tool in ++"orientations" . sunshields with azimuth

In substance, it means sun-shields arrangement yield will always be low compared to other PV systems: mutual shadings are really very high, and quite unavoidable.

The only acceptable layout is the upper row: if it is at the top of the building, it is indeed a "perfect" PV collector disposition, even without the building's wall shading.