Solar Survey

Solar survey of the library site

Thorsten Chlupp of Reina Alaska has conducted a survey of the solar gain to be had at the librarybuilding site. The survey was submitted to the JTEL Board of Directors September 1, 2011. For the complete report, download the PDF below.

Download Solar Access and Shade Report

Summary and notes from the report:

This solar study was conducted with a Solmetric SunEye 210 at three independent site visits during different times in the afternoon and at different location on the lot to determine the annual solar gain. This is essential information we need for the passive and active design of the building and the solar system. The SunEye 210 is an integrated Shade Analysis Tool for solar site assessment. It includes a fisheye camera and a dedicated on-board processor and GPS system to perform digital image processing and analysis to compute shading and solar access percentages. It includes an electronic compass and inclinometer enabled to measure roof pitch and azimuth.

A proper site survey reveals the actual path of the sun across the sky during the entire year. Especially in our far north latitude and the resulting drastic change throughout the year of the suns angle on the horizon makes it important to take the various angles into close consideration in the design and placement of windows and solar panels.

The results on the actual building should be better due to the fact that the collectors will be mounted several feet higher than where the current measurements were taken. This will help to clear shading from the lower tiered trees which will shade the building some. However the window gains from the south will be lower and provide less solar input into the building in the darkest months – December and January are simply grim in Fairbanks.

My overall conclusion is that the site is definitely feasible for the proposed building and its renewable energy systems. It is not ideal, but has no major obstacles in the sun path.

Key to terms and abbreviations used in the study:

  • Solar Access: The annual and seasonal solar access is shown in the Results panel. The seasonal month ranges, May-Oct and Nov-Apr, represent the common peak and off-peak rate seasons. Your local utility may use a different set of months.
  • Solar Resource: Tilt Orientation Factor (TOF) and Total Solar Resource Fraction (TSRF) are used to compare the actual site characteristics to the optimal characteristics at that site. TOF and TSRF can only be displayed when the NREL – TMY3 weather model is selected (US only).
  • Windowed Access: Calculates solar access only within a window of time in months and time of day. The user specifies the months and time window and solar access is calculated only for that window. Note that the insolation both with and without shading is windowed, so if there is no shading within the defined window, then the Windowed Access would be 100%, even if there is shading outside the window.