Shading analysis

 

Sunpath

Analysing the sunpath diagram, the house would get a 0 for orientation. Bedrooms and kitchen, at the back of the house, don’t have any direct sunlight from half October till the end of February. More than 50% of the windows point in this direction. In the summer, the bedroom does get the morning sun, which is good.










July shading during a day                                    January shadings during a day

 

Roof shading

Before thinking of putting solar collectors or pv modules on the roof, it should be analysed for possible shading losses. Are the trees shading the roof ? Is the main roof shading parts of the other roofs? 

The left picture shows the shading levels on the roof without trees in October. The right picture clearly indicates shading on all the “sunny” roofs by the trees. The roof above the workshop in front of the picture is also partially shaded by the main building. This, and the low tilt angle, would make this part of the roof an inefficient place to put solar modules.

As trees are less of an issue to cut short, there are only two roof surfaces viable for solar energy:

  1. 1.Main roof above habitation and barn, South-East side

  2. 2.Less suitable but still fine; living roof pointing South-West

 

Which roof part has got the most irradiation?

In order to determine the best roof part to put solar devices on, a irradiation analysis is needed.  There are two possible roof orientations: S-E (-36°) or S-W (54°), assuming South is azimuth=0°.

  1. 1.The incident solar irradiation analysis on the roof above the living room (54°):





  1. 2.The incident solar irradiation analysis on the main roof (-36) :



These are nice graphs, where we do see a dip in june, but it’s hard to compare both. Plotting the results in a spreadsheet will give a better idea :



The irradiation on the main roof is slighty higher than the one in the living room’s roof. the difference is 58.64 kWh/year.










The shading of the roof surfaces clarifies a lot of the above data. Shading losses of the living room’s roof are much higher, due to shading from the trees and from the main roof, as discussed in the beginning of this page. Therefore, installing a solar system on the living room’s roof is less advisable.