The gap between the last row of solar panels and the roof's edge should be a minimum of 12 inches or one foot. This ensures the panels are accommodated as they expand and contract during the day.
How do you calculate the space needed for a ground-mounted solar system?
To estimate the total space required for a ground-mounted solar system, you can use the following formula: Multiply the number of panels by the area of a single panel. For example, if each panel is 1.7 square meters and you're installing 20 panels: Add the space needed between rows.
Solar panels must have at least 4 to 7 inches of space between rows because the frame contracts and expands as the weather changes. There must also be at least 12 inches of space between the solar panel and the edge of the roof to comply with building codes and to keep the array secure. Why is There a Gap Between Solar Panels?
Check the racking mount instructions for the specific number. Here is an example with the solar panels to be installed in portrait. Each panel is 65 inches long and 39.4 inches wide. For convenience the width will be rounded to 40 inches. The roof space is 360 inches (30 feet) in length and 240 inches (20 feet) from bottom to top.
On the average roof, the space for your rafters is equal to 16 inches. The standoffs have a 48-inch space between each of the posts. This means that if you decide to install four PV modules that each measure 65 x 39 inches, the total dimension equals 160 inches. So, if your rail is 160 inches long or more, you'll have enough room for your panels.
Modules offering 375 watts would require only 25 to 30 of them for your roof. Today, most solar panels for homes are 250 to 375 watts. A general rule should be 1 kW for every 3.5 panels for a module that offers 285 watts. Therefore, for panels that are 340 to 375 watts, you would only require three panels.
The gap between the last row of solar panels and the roof's edge should be a minimum of 12 inches or one foot. This ensures the panels are accommodated as they expand and contract during the day. See also: Mounting Solar Panels: A Complete Beginner's Guide to Installation How Much Gap Should Be Between Two Solar Panels?