Solar Panel Roof Requirements
When deciding to purchase a home solar energy system, most homeowners choose to mount the solar array system onto their roof.
Putting a solar panel on the roof means roof design and condition become a large factor in both the system design options and in the initial cost.
Understanding roofing requirements and the basics of roofing structures can help you make a more educated decision about your solar panel system.
Since the installation for a roof-top solar panel system is a long-term commitment, it’s best to ensure that your roof is in good condition before the project starts. However, systems can be temporarily removed for construction purposes. If your roof needs to be replaced or otherwise updated, the money you could save on solar installation from the Renewable Energy Tax Credit could be reinvested into the home structure and roofing.
The amount of space available for mounting panels and the orientation of roof surfaces is critical to getting the most out of any system. Each solar module is approximately 5.3 feet long and 3.2 feet wide or just about 17 square feet per module. The minimum number of modules for our smallest residential grid-tied system is 4 modules, so you’ll need roughly 80 square feet of roof space in order to install a roof-mounted array system.
The most basic roofing structures are hip and gable types.
A hip roof is the kind in which all sides of its roofing slope downwards towards the walls of the building. The hip itself is the angle at which the slopes of the roofing meet, and the degree of this angle is called the hip bevel.
Gable roofs are the simplest kind of roofing, yet are available in a range of variations. All gable roofs constitute two flat slopes that are joined together to form a ridge, thus creating a peak or triangle on the wall of the front. The word gable refers to this triangular shape.
Some roofs by design have a greater number of surfaces, such as mansard and gambrel. Simple designs can also be made more complex.
The gambrel roof can best be described as a mix between a gable and a hip roof. It is two-sided with a double slope on each side. The lower slopes are positioned at a steep angle, while the upper slopes are relatively flat. This style of roof quite often has many surfaces.
The mansard roof is characterized by four sides, each double-sloped, the lower slope being significantly steeper than the one above it. The upper slope is not usually visible from the ground, as it is angled only enough to allow the run-off of water.
Complex Hip and Gable
As housing shapes deviate from rectangular to L-shaped and beyond, the associated hip and gable structures become more complex, with more than four basic surfaces and more than four simple orientations. Some can have dozens of different surfaces. Cross gable designs are the most common complex types, in which perpendicular housing sections carry gable roofs perpendicular to the original roof
Orientation and pitch of the surfaces on which to mount the solar panels will have the largest impact on performance and therefore the value of the investment. To some degree this can impact cost and design as well.
In Ohio, the sun is always to our south, so roofs ideally should face true south. However, surfaces facing east, southeast, southwest or west can also work. Roof pitch becomes more critical as the orientation deviates from true south. Contact us to learn more about how YellowLite can maximize your design for certain combinations of orientation and structural design.
The roof pitch is a numerical measure of the steepness of a roof. It is expressed as a ratio of vertical rise to horizontal run, or in inches of rise per foot of run. Ideal pitch is approx equal to site latitude.
Many homes include chimneys and associated crickets, vents and vent pipes, skylights, dormers, and other shapes that create two obstacles for installing solar panels. First and most obvious, they must be avoided, which requires bypassing some amount of valuable roof space. They can also add shading concerns to adjacent panels.
Curves and Flairs
For the most part, curved surfaces that are not flat should be avoided.
Why is shade a problem?
Because of the wiring design of a solar module, all of the individual solar cells on a module must receive full sunlight for the module to work properly. If any portion of the module is shaded, the entire module's power output-even those sections still exposed to sunlight-is lowered.
What if I need a new roof or am building a new house?
This is the ideal situation for installing solar. Before laying the roof, you can install flash-able mounting brackets that provide the highest level of protection from leakage. Although it is easier to incorporate solar during a reroof or new construction, most installations aren’t done under these circumstances. Reroofing a home after a system is in place is not a difficult hurdle. When it is time to reroof a home we are glad to assist with removing the panels so construction proceeds smoothly.
Is there any problems with roofing leaks after installation?
All installations are weather-sealed so that there is no threat of leaky roofs. If a leak does occur, and the leak is determined to be directly contributed to the solar installation, all repairs will fall under the YellowLite labor warranty and will promptly be corrected.