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<< Click to Display Table of Contents >> Sun-shields shadings |
  
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<< Click to Display Table of Contents >> Sun-shields shadings |
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In the "Orientation" option and for near shadings, sun-shields are treated in a similar way as sheds (see Shed Mutual Shadings discussion).
Nevertheless, the user should be aware of two phenomena:
| - | With sun-shields, the accepted part of the diffuse irradiation is very limited: on one hand, there is at most only one half because of the rear wall, and on the other hand the upper sun-shield also cuts an important fraction of the remaining diffuse component. In regions with a high diffuse fraction (above 45° latitude, it is usually more than 50%), this gives a very significant loss. |
| - | Please be very careful with orientations not exactly facing the south (or north in southern hemisphere). You can use the special tool "Shading graph" to visualize this dramatic effects. But even with south orientation, the mutual shadings in the morning and evening are not avoidable. |
The sun-shield is not suited for low latitudes, where the sun's height is high during the day.
To our mind, the sun-shields arrangement is not a good situation for a good PV yield. The 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.