Sun charts provide information related to the solar resource available at a site and are used to determine the amount of energy a given system should generate. All Energy Trust incentive applications must include a sun chart. Solar Trade Ally Contractors may use either:
- A conventional sun chart, available in Cartesian and Polar variety. These sun charts are completed by hand, but contain all the information necessary to complete an Energy Trust incentive application.
- A report and sun chart from an Energy Trust approved site analysis tool. The report must include a data column that represents the equivalent of solar resource available after shading. The Tilt & Orientation factor (TOF) must be pulled from an Energy Trust contour plot or sun chart.
Currently approved for submission with Energy Trust incentive applications are reports from the Pathfinder Site Analysis Tool Assistant Software, Solmetric SunEye Shading Analysis Tool, and the Wiley ASSET Solar Site Evaluation Tool. For detailed instructions on using these tools and displaying the required information, please refer to the following documents:
Still confused about sun charts?
Below is a summary of where the solar site information required on Energy Trust’s incentive applications can be found.
Solar Resource Information
Determine how the annual solar resource available to this system will be reduced by shading and suboptimal tilt/orientation of the array. Please use the Energy Trust sun charts.
| |
%
|
Solar resource available after shading losses. |
100% - _____% annual shading. Calculate using the applicable sun chart. |
| x _____ |
% |
Solar resource available after tilt and orientation losses. Tilt and Orientation Factor (TOF) |
From sun chart; percent of annual electricity produced, relative to an optimal system. |
| = |
% |
Total solar resource fraction (TSRF). Annual solar resource available after shading, tilt and orientation losses |
Must be greater than 75% to quality for Energy Trust Incentive. |
Performance Estimate
| _____________kWh/Watt yr |
Local Production Capacity |
From sun chart; Annual production capacity per |
|
|
Solar resource available after shading
|
Tilt & Orientation Factor (TOF)
|
Local Production Capacity
|
|
Energy Trust Sun Chart
|
100% - shading (calculated on sun chart)
|
% stated in the 4th paragraph on sun chart
|
3rd paragraph on sun chart in kWh/wattDC per year
|
|
Pathfinder Assitant
|
"Actual Shaded Solar Radiation” divided by “Actual Unshaded Solar Radiation" report column
|
"Actual Unshaded Solar Radiation" report column
|
See Chart Below
|
|
Solmetric SunEye
|
“Annual Solar Access” report column
|
Contour Plot or sun chart for nearest city
|
See Chart Below
|
Contour plots are available at the same webpage as the sun charts.
Local Production Capacity and Ideal Tilt & Orientation for Oregon cities
|
Site Location
|
Ideal Tilt
|
Ideal Azimuth
|
Local Production Capacity (kWh/wattDC per year)
|
|
Astoria, Seaside, Cannon Beach, Warrenton
|
34°
|
191°
|
1.03
|
|
Burns, John Day, Canyon City, Hines
|
34°
|
175°
|
1.39
|
|
Eugene, Springfield, Sweet Home
|
30°
|
190°
|
1.14
|
|
Hood River
|
34°
|
178°
|
1.19
|
|
Klamath Falls
|
34°
|
176°
|
1.47
|
|
Medford, Grant's Pass, Ashland
|
32°
|
185°
|
1.32
|
|
North Bend, Coos Bay, Coquille, Bandon
|
33°
|
188°
|
1.26
|
|
Pendleton, Enterprise, La Grande
|
35°
|
177°
|
1.31
|
|
Portland, Hillsboro, Oregon City
|
32°
|
190°
|
1.08
|
|
Redmond, Bend, Prineville, Madras
|
36°
|
175°
|
1.43
|
|
Roseburg
|
33°
|
192°
|
1.20
|
|
Salem, Lincoln City, Corvallis, Silverton
|
32°
|
189°
|
1.14
|