Tool for assessing the annual solar resource occlusion

Tool for assessing the annual solar resource occlusion

There are many tools available to assess the occlusion situation of the site throughout the year. The following example only needs to survey the site once to evaluate the solar energy resources throughout the year.

⑴Solar Pathfinder
Solar Pathfinder is used to determine the occlusion of alternative photovoltaic installation sites. It is used to identify the objects that will cause the occlusion and the time of the year when the occlusion occurs.

Solar Pathfinder requires a map of the solar path at the latitude of the site. This image is placed inside the Pathfinder. Rotate the image so that the white point on the sideline is at the field magnetic declination, and then rotate the Pathfinder as a whole to make the needle eye on the base point align with the magnetic north direction. Then, put a transparent top cover on Pathfinder.

When Pathfinder is placed at a given location, its surrounding objects will be projected on the top cover (and on the internal path diagram), and these shadows will be marked on the solar path diagram with crayons to determine where the photovoltaic array on the site is Sometimes it is blocked. If there is no projection on Solar Pathfinder, the site will not be blocked throughout the year.

The arc on the horizontal plane represents the sun’s path in the sky in each month of the year. In Figure 2, there is a large tree on the north side of the site. Except for November,December, and January, the array will be obscured during certain time periods of each month. The vertical line represents the hours of the day: throughout the year, this array will be blocked before 8:00 AM.

Although Solar Pathfinder is an outstanding tool, it is not always effective. If the building where the photovoltaic array is located has not been built, Solar Pathfinder cannot be placed at the same physical height as the array. After the building is completed, it is possible to make a comprehensive assessment of the impact of the photovoltaic array. Solar Pathfinder also has supporting software: users do not need to draw shadows on the sun path diagram, but take a photo of the top cover and upload it to the computer. This software can also raise the ground plane to a given height for occlusion analysis, making it possible to use Solar Pathfinder even when it cannot be placed at the physical height of the photovoltaic array.

Tool for assessing the annual solar resource occlusion
Figure1 Solar Pathfinder, showing the trees in the north and the occlusion situation on the right side of the site

⑵Solmetric Suneye
Solmetric Suneye is a digital tool that will be placed flat on the future installation site. The user must specify the latitude of the site. It uses the horizontal lens of a fisheye camera to take pictures and analyzes the influence of surrounding objects. You can purchase accessories such as GPS units to improve the accuracy of the analysis. Suneye also has a level and inclinometer function, which can measure the angle and orientation of the roof.

Tool for assessing the annual solar resource occlusion
Figure 2 is an example of drawing the occlusion situation on the sun path diagram; for the latitude of the site, it is very important to use the correct solar path diagram

HORlcatcher is another widely used digital tool. Install a digital camera on the horizontal mirror, upload photos, and use related software to calculate the available radiation on site.

Tool for assessing the annual solar resource occlusion
Figure 3 Solmetrie Suneye
Tool for assessing the annual solar resource occlusion
Figure 4 HORlcatcher in use

⑷iPhone application software
The company also has a large number of iPhone applications that can be used to draw horizontal planes and provide on-site analysis. These applications include:

①Solar Checker software can access the database and determine the amount of solar radiation for a site with a GPS location. Then use iPoe’s magnetic induction compass to measure the heading of the house, and use the internal sensor to determine the inclination. Using these data, Solar Checker uses a mathematical model to estimate the annual output power.
②Solmetric iPV Solor APP also belongs to the company that manufactured Solmetric Suneye. The application software is not expensive and not as powerful as Suneye. iPV can adjust the roof sail direction and inclination angle, estimate the effective solar radiation, and generate on-site investigation reports.

⑸ Software package
In addition to the software released with the tool, there are also some simulation programs that can be used to analyze the shading effect of the photovoltaic array. In order to use these procedures effectively, the physical dimensions of the objects related to the array site must be determined. Build a three-dimensional computer model of the scene and array, and then the program can simulate the projection of these objects. Such software includes:
① Shadow Analyzer.
②Ecotect: This is an architectural tool software, which can also be used to analyze building heat and energy.

Tool for assessing the annual solar resource occlusion
Figure 6 Screenshot of the architecture software, showing the three-dimensional model of the house and photovoltaic array