Renewable Energy Ready Home Solar Site
Assessment Tool

The Renewable Energy Ready Home Solar Site Assessment Tool is intended to guide home builders in assessing whether a new home has the proper physical orientation to support a future installation of a solar energy system. This tool evaluates the proposed site's solar resource potential based on a series of known factors about the home at the time of construction, such as the home's location and anticipated shading effects at the proposed site. New homes that are found to provide a suitable installation environment are considered good candidates to be outfitted by the builder with the structural and system components needed to support the cost effective installation of a future renewable energy system. For further information on the elements of each specification, please see EPA's Renewable Energy Ready Home Specifications. For questions about RERH please contact James Critchfield at critchfield.james@epa.gov or 202-343-9442.


calculator assessment banner for RERH

How the tool works

Builders should input information into the tool about the proposed home and system site location. The solar site assessment tool uses this information to estimate the site's solar resource potential and compares that to an optimal solar resource potential for the same location. A site with an optimal solar resource potential will typically have a 180 degree orientation, a roof inclination roughly equal to the site's latitude, and a percentage shading of zero. Proposed site locations that achieve a minimum of 75 percent of the optimal solar resource potential are considered good candidates to be outfitted as renewable energy ready. The tool does not predict future system output.

What you need to get started:

  1. Enter the location of the home (ZIP code or Latitude and Longitude coordinates)
  2. Enter the orientation of the proposed array surface (Azimuth in degrees)
  3. Enter the roof inclination/pitch of the proposed array location (Degrees off of horizontal)
  4. Enter the percent shading at proposed array location (Based on a solar path tool assessment)

Site Location

Required Site Location Information

 

More information Format: XXXXX or ZIP+4
Enter the associated Zip Code for the proposed solar array site. When entering a Zip Code use a 5-digit Zip Code, a Zip+4, or a 9-digit Zip Code format, see examples below. The Zip Code is used in the tool to assess the solar resource potential for the proposed site using the National Renewable Energy Laboratory's PVWatts web service.

Examples:

5-digit ZIP Code:
ZIP+4:
9-digit ZIP Code:

90210
90210-3100
902103100

- OR -


 

More information Format: DDD.dddd°
Enter the associated Latitude & Longitude for the proposed solar array site. When entering the Latitude & Longitude use a decimal degree format (Example: 81.654°). The Latitude & Longitude are used in assessing the solar resource potential for the proposed site using the National Renewable Energy Laboratory's PVWatts web service.

Optional Site Location Information More information
Input optional site information to better describe or indentify the location of the home. These data inputs are not used in assessing the solar resource potential for the proposed site.

All data inputs in this sub-section use a text format.



Array Position

More information
Enter the orientation azimuth (in degrees) of the outward facing roof plane at the proposed array location. Assume all roof mounted arrays will be mounted flush against the roof.

Examples:
  90° = East
135° = South East
180° = South
225° = South West
270° = West

Refer to the Renewable Energy Ready Home specification document for further information.
More information
Enter the degrees inclination (in degrees off of horizontal) of the roof plane at the proposed array location.

Assume all roof mounted arrays will be mounted flush against the roof.

Examples:
  0° = horizontal or flat roof
90° = vertical

Refer to the Renewable Energy Ready Home specification document for further information.


Percent Shading

Would you like to use annual or monthly percent shading data?

More information
Enter the percent shading impact for the proposed array location.

The percent shading input should be determined by using an industry acceptable sun-path tool.

Input values may range from 0 to 100 percent.

0% = no shading
100% = fully shaded site location

Refer to the Renewable Energy Ready Home specification document for further information.













What's Next?

After entering the required site information into the tool and hitting the calculate button, the user will receive a site assessment indicating whether the home offers a suitable solar resource. Homes that demonstrate a suitable solar resource potential are good candidates to be outfitted as renewable energy ready.

For homes that fail to demonstrate a suitable solar resource potential, builders are encouraged to propose alternate array site locations. The site assessment results are influenced by data inputs for array orientation, array tilt angle and array shading percentage.