OpenUtilities Substation Help

Solar Exposure Calculation

The Solar Exposure Calculator produces both solar radiation and shadowing analysis over a user-defined time period.

While shadow geometry is effective for visualizing and analyzing instantaneous sunlight effects, it is often necessary to analyze the cumulative effects of sunlight. This is important in designing buildings for optimum heat loss (or gain) as well as placing photovoltaic panels for energy generation.

The Solar Exposure Calculator performs an analysis of the amount of solar exposure that is received during a user-specified time period. It accumulates both the total time (and shadowed) time as well as the solar energy or Insolation (Incident Solar Radiation) received.

Getting Weather Data

Currently, only the EnergyPlus Weather Data (EPW) format is supported. The primary source for data in this format is the U. S. Department of Energy. Go to the Energy Efficiency & Renewable Energy site and browse by location. When you have located a data set for the relevant area, look for a link to an EPW file. If there is such a link, this is the file you need. If not, download the ZIP file, which will contain a file in the EPW format.

If you cannot obtain EnergyPlus Weather data for your location, you may be able to convert data from another format. The EnergyPlus Weather Converter supports a number of formats, including TMY, TMY2, IWEC, WYEC2, SAMSON, DOE-2, ESP-R, BLAST, and SWERA. If you have data in one of these formats, download the EnergyPlus tools and use the Weather Statistics and Conversions program to convert the data to the EnergyPlus Weather format.

Solar Exposure Calculator Output

The results from each solar exposure calculation are generated in a new model, either within the current file if the Output is set to Model or to a new design file if the Output is set to Design File. The output model contains intelligent mesh objects that represent the solar exposure calculations for each element in the input file.

Analyzing the Solar Exposure Results

A separate Solar Exposure Mesh is created for each element in the source file. These intelligent objects encapsulate all of the solar exposure information, including insolation, exposure and shadowing data.

You can access the solar exposure information at a particular surface location by:

  • Pop-up Info — Pause the cursor on the element and the insolation values as well as the exposed and shadowed data for the facet appear below the cursor. Information for a single insolation grid facet is provided. This setting is controlled by the Pop-up Info setting on the AccuSnap Settings dialog General tab.
  • Properties — The Properties dialog for a Solar Exposure Mesh includes a comprehensive listing of all of the solar exposure data for the selected element. The information included is either the cumulative value (for Area, and Insolation) or average value for Shadowed and Exposed hours. The Start and End indicate the solar exposure calculation interval.

Controlling the Solar Exposure Mesh Display

The display settings for solar exposure models is tied to thematic display , which is set in the Overrides section of the Display Styles dialog. Most of the options available for solar exposure are also available for other thematic display types.

Note: Solar Exposure Mesh elements do not display in versions prior to OpenUtilities Substation V8i (SELECTseries 3).