Before designing or installing a solar energy system, it’s important to determine how much solar energy your site receives.  To be eligible for most financial incentives, you will need to demonstrate that your site meets some minimum solar resource requirements.  If you hire a solar contractor or a passive solar design architect, they will perform the solar site analysis for you.

A solar site analysis will evaluate the combined effects of:

Orientation:

Maximum solar energy will collected with your building or solar panels oriented true south.  Use a compass to measure your site’s magnetic south, then adjust for magnetic declination to locate true south.

Shading:

Summer shading may be desired in passive solar design, but is detrimental to solar electric or solar water heating system output.  A shade evaluation tool such as a sun chart or solar pathfinder is used to analyze the impact of shading on your site.  These tools show the daily path of the sun across the sky during all hours and all months of the year.  The impact of shading can be calculated by mapping (manually or photographically, depending on the tool) all of the items that will block the sun's rays, such as trees, hills and buildings.  Be sure to note items such as trees and planned construction that might shade the site in the future.  Also consider that morning or afternoon shading will be more detrimental to solar panels facing east or west, respectively. Contractors will typically perform a site analysis when you ask for a bid. You can also rent a Solar Pathfinder here and do your own site analysis.

Tilt angle:

Solar panels can be tilted at a variety of angles and still allow solar electric or solar water heating systems to work effectively.  You may choose the tilt of your solar panels to result in the best aesthics and ease of installation, for maximum annual energy production, or for targeted seasonal production.

Learn more about how to site a solar electric or solar water heating system.