Solar
irradiation distribution on a dome in Athens
by Thanos N.
Stasinopoulos |
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posted 08.03.02 |
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The polar graphs below illustrate the distribution of daily
global irradiation
on a hemispherical dome located in Athens, Greece during the months of March,
June, September & December
(months indicated by red
digits). |
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Each point of the dome is associated to a point on the graph according
to its orientation & slope. |
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The white, yellow,
orange & red
curves refer to slopes of 90, 60,
30 & 0
(horizontal) respectively.
The curves on the left side refer to
intermediate slopes at steps of 10 (their symmetrical right half is
omitted for clarity). |
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The distance of each curve point from the center denotes the radiation
value for the associated orientation & slope. |
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The graph scale is indicated by the dotted semi-circles
on the right, at radius steps of 1 kWh/m. |
| Use |
| The graphs can be used to
read monthly radiation values for any given orientation & slope in a
manner similar to polar sunpath diagrams. |
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Additionally, they provide an easy tool to
study the seasonal variations of solar intensity at various directions. |
| Further
development |
| The graphs shown here are
a few samples of a set of graphs that can offer a useful tool for solar
applications. |
Additional graphs for
- months not included here,
- annual & winter sums,
- direct & diffuse radiation, and
- other locations (London & Riyadh)
can easily be produced from readily available data. |
| A 3D version is under
development. |
| Sources |
Data of global radiation incident on each section -depending on its
orientation & slope- was taken from [1], for average sky conditions
and ground albedo 0.2.
Graphs were plotted from numerical data using AutoCAD via a special AutoLISP routine
developed by the author for this purpose. |
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The
author is seeking support
for
further development & dissemination of the tool.
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North
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Reference
[1]
Stasinopoulos T. N., Geometric Form & Insolation, PhD
dissertation, National Technical University of Athens, 1999 [English
summary]; radiation data has been calculated following the algorithm in
Page J. K. (edit.), Prediction Of Solar Radiation On Inclined Surfaces
Vol. 3, Reidel/CEC, 1986.
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