The Solar Position Panel sits within the main application window and controls the date and time at which some of the detailed solar analysis is performed as well as the orientation of the test surface on which solar incidence is calculated. You can open and/or close this panel by clicking in its title area. If you click on the status icon on the right-hand side, the panel will open/close without affecting any of the other panels around it.
Editing Numeric Values
When editing any of the numeric values in this panel, you can use the PageUp/PageDn keys or the mouse wheel to increment/decrement the current value whenever the edit box has the input focus. Holding down the Shift and Control keys will increase or decrease the current increment/decrement values. If you manually enter a new value, remember to hit the Enter key to apply your changes to the model.
Graphical Display
When this panel is selected, the display changes to show a Sun-Path Diagram. These are a convenient way of representing the annual changes in the path of the Sun through the sky on a single 2D diagram. Their most immediate use is that the solar azimuth and altitude can be read off directly for any time of the day and day of the year. They also provide a unique summary of solar position that the designer can refer to when considering shading requirements and design options. There are quite a few different types of sun-path diagram, however the Weather Tool only includes two main forms, described below.
Panel Controls
The following is a description of the items available in this control panel.
Display Type
This button displays the menu shown immediately to the right. Thie items in this menu determines both the type and format of information is solar display.
Orthographic Projection
A orthographic projection is simply a 2D graph of the Sun position in Cartesian co-ordinates. The azimuth is plotted along the horizontal axis whilst the altitude is plotted vertically. Reading off positions is simply a matter of reading off values in the two axis.
Stereographic Projection
Stereographic diagrams are used to represent the sun's changing position in the sky throughout the day and year. In form, they can be likened to a photograph of the sky, taken looking straight up towards the zenith, with a 180 fish eye lens. The paths of the sun at different times of the year can then be projected onto this flattened hemisphere for any location on Earth
Tabulated Data
Select this item to display a table of solar data including sunrise/sunset times as well as hourly azimuth/altitude and HSA/VSA values.
Overlay Hourly Data
The items in this sub-menu allow you to display changes in the different weather parameters as a function of sun position. As an example, if you selected to overlay temperatures, you would typically note from the resulting diagram that the coloured scale indicates that higher temperatures tend to occur towards the centre of the stereographic diagram, when the Sun is higher in the sky.
Annual Solar Radiation
This item displays a map of daily total solar radiation shown over the whole year. The thick yellow line represents the 30 day running average whilst the thinner, darker line shows the actual recorded total daily solar radation. The red and blue areas of the graph indicate the three hottest and coldest months respectively.
If you adjust the orientation of the collection surface using the slider, you will see that the curve varies quite significantly. The aim here is to adjust the orientation such that you maximise solar collection in the three colests months whilst at the same toime minimising it for the three warmest.
Best Orientation...
This item invokes the Optimum Orientation dialog.
Chart Highlights
The items in this sub-menu allow you to highlight the different components of the currently displayed sun-path diagram. The selected component is then displayed in yellow until another component is selected. You can turn off the highlighting by simply choosing again the currently selected sub-menu item. The default is to highlight the current Sun position.
Display
The items in this sub-menu determine what is displayed within the diagram, currently limited to the Title, the Legend and the Axis markers.
Date/Time Settings
These controls set the current date and time. This determines the position of the Sun in the sky - which is displayed as a yellow circle in the Sun-Path diagram and as shadows on the surfaces of the 3D Window Model.
Time and Date Values
The top two edit boxes allow you to enter date and time values directly whilst the box. The selector immediately below allows you to choose the month of the year. When you select a month, the current date value is checked and modified if necessary to fit within the range of possible days in that month.
Daylight Savings
This basically increments local time by one hour to account for daylight savings. This is a manual switch that does not automatically determine if a location is on or off daylight saving.
Orientation
This slider adjusts the orientation of the collection surface. This surface is indicated in red within the Sun-path diagram and will interactively rotate as you adjust the slider. The square or triangular projection indiates which side the surface is facing.
Solar Radiation button
This button displays a map of daily total solar radiation shown over the whole year. The thick yellow line represents the 30 day running average whilst the thinner, darker line shows the actual recorded total daily solar radation. The red and blue areas of the graph indicate the three hottest and coldest months respectively.
Pressing the >> button animates the display by rotating the collector surface and recalculating the entire annual incident solar radiation graph each time. Press the button again to stop the animation.
Best Orientation... button
This item invokes the Optimum Orientation dialog.