SUN_CHART Solar Design Software

SUN_CHART Solar Design Software logo.

Calculates and screen plots both cylindrical and polar suncharts for any desired latitude. A sunchart is a map of the sun's path across the sky during the year. Even though its path changes from day to day and from latitude to latitude, the position of the sun at any time on any day of the year is entirely predictable. SUN_CHART also performs shading calculations and plots these shading diagrams directly onto the desired cylindrical sunchart. SUN_CHART can be used for:

  • Calculating and plotting whole year cylindrical suncharts for any latitude.
  • Calculating and plotting whole year polar suncharts for any latitude.
  • Calculating and plotting single day suncharts for any day of the year for any latitude on earth in either cylindrical or polar format.
  • Calculating and plotting shading diagrams superimposed on top of a sunchart for any overhang/column combination for windows facing any direction.
  • Converting between sun time and actual time for any latitude and longitude for any day of the year. This feature will provide accuracy to within a few minutes.
  • Calculate the time of sunrise, sunset, and solar noon to within a few minutes for any day of the year for any latitude and longitude.


sunchart, solar position, sun path, shading



Expertise Required

No special expertise or training is required. An explanation of sunchart uses and applications is given in many solar energy books and is also provides as a service on the author's web page, Passive Solar Design Using Computer Generated Suncharts.


Total number of users estimated to be over 100. Most users are currently in the US, but several software packages have been exported (Israel, Far East).


Professional and amateur solar designers, architects, engineers, students, etc.


For most calculations, only the user's latitude is necessary. Some calculations also require the user's longitude. Shading calculations require building geometry values to be input.


Most calculations are usually presented as a graphical sunchart as shown above.

Computer Platform

Operates on any 386 or higher computer under DOS or Windows.

Programming Language

Provided in compiled form only and runs under DOS operating systems. It will also run under WINDOWS, but is not presently a WINDOWS program. A WINDOWS version is currently being developed.


Useful in calculating and accurately plotting both cylindrical and polar suncharts and in performing shading calculations. It also performs some other minor functions.


Not currently a WINDOWS program even though it can be run under WINDOWS.



Optical Physics Technologies


PO Box 51483
Idaho Falls, Idaho 83405-1483
United States




The cost of SUN_CHART is $75.00 plus shipping ($3.00 US, $5.00 Canada & Mexico, $8.00 other countries). For more information on using suncharts in solar design and in ordering SUN_CHART software see the web site.