When installing solar panels on the roof you have to consider many things. If your roof is not suitable to fix enough solar panels to produce enough energy for your house there is no point in installing solar panels.
Most of the time your solar system provider is the one that decides this for you. When deciding that they mainly consider about following factors; Size, weight capacity, roof material, roof age, roof shape, roof direction, roof pitch, and shade.
So in this article, we will cover all these factors and how they affect your roof eligibility.
Is your roof big enough to install solar?
When we are installing solar panels on the roof, the size of the roof is one of the major limitations. If we cannot fix enough solar panels on the roof we cannot get enough electricity from the solar panels.
Average 2000 sqft house use about 32 Watts per day. If we use 300 W solar panels in this house solar system and the area’s average number of sun hours is 4.5, we need about 20 -25 solar panels to produce enough energy.
If you use solar panels with a higher Watt value, you need fewer solar panels.
To fix all the solar panels we need approximately 450sqft of clear roof space.
The problem is due to the various roof designs and structures like chimneys, vent pipes. Skylights, etc. on the roof we cannot get this roof space as direct, clear space. Sole panel installers will work around these obstacles and fix the panels according to the shape of the roof.
But this can affect the installation cost.
Is your roof weight capacity is enough to install solar?
Roof weight capacity is the value that indicates how much load your roof can withstand.
Knowing this value is very important when installing solar panels as the weight of the solar panels adds an extra load on the roof. If you exceed the roof weight capacity the roof will collapse. So exceeding roof weight capacity is very bad for your safety.
The weight capacity of the asphalt shingled roof is about 20 pounds per sqft. The weight capacity of a concrete or clay roof is about 27 pounds per sqft.
Even though roofs were built to have this weight capacity this value reduces with time as a result of roof aging. So knowing the current weight capacity of your roof is important.
The average weight of a solar panel ranges from about 20 – 50 pounds. So before installing solar panels you have to find out the total weight of your solar system. This includes all the solar panels and the mounting system. Then you have to make sure the total weight is below the extra load that can put on your roof.
Read more about roof weight capacity.
Is your roof material suitable to install solar?
When thinking about the suitable material you have to keep in mind, that solar panels have about 25 years of a lifetime. That means if you use less quality material or materials with less lifetime, you have to repair your roof from time to time.
This will cost you more because you need to remove the panels and reinstall them every time you want to repair your roof.
Asphalt shingle roof is best for installing solar panels. They are durable and very strong. Because of the extended lifetime, they are more suitable as you do not need to repair much.
The process is very straightforward when installing solar panels on asphalt shingle roofs. You do not have to remove or replace the roof to fix the panels. Installers simply drill the holes on the roof and fix the panels by using bolts.
Concrete, clay, or metal are also good options as roofing materials when installing solar panels.
When installing solar panels on concrete and clay-tiled roofs, you have to remove the tiles on fixing areas and fix the panels as they can break due to the weight of the workers. Also, when fixing solar panels on these types of roofs you have to directly fix the panels to the roof, not to the tiles.
Installing panels on metal roofs is easier and they also very suitable to install solar panels.
Concrete flat roofs are very common. Sometimes there is no need to fix the panels onto the roof. But when installing panels on flat roofs you need an angled mounting system to get a better output.
Wood roofs are not recommended as they age faster when compared with roofs made from other materials. Also, wood roofs are not recommended as there is a fire hazard.
Slate, cedar, and rubber roofs are not much recommended as they are not designed to add anything on top of them.
But some solar roof providers have facilities to install solar panels even on these roof types by installing panel supports. But this has to be done before building the roof. Otherwise, you may have to replace your roof.
Is your roof too old to install solar?
Your roof is made using many materials. They have a certain lifetime. With the age, these materials wear off and the weight capacity of the roof reduces.
If your roof is newly built you do not have to worry about this. But if your roof was built a while ago you must hire someone to inspect your roof before installing solar panels.
Most qualified, professional solar installation companies do inspect your roof and load that your roof can hold before going to further steps.
If your roof is more than 10 years old it is safe if you replace your roof before installing solar panels. With aging your roof tends to get damaged pretty easily. So if you install solar panels on an old roof you have to remove and reinstall your panels many times as your roof needs more repairing.
Also, it is dangerous to work on an old roof. Someone can easily get hurt. Also, if the roof weight capacity is exceeded roof can easily collapse.
How roof shape affects solar panel installation?
With the evaluation of the architecture, we can see many roof designs. Roof designs greatly affect the available clear space to install solar panels. Also, this affects the amount of sunlight that is received to the rooftop. Not just that the roof design also affects the weight capacity of your roof.
So your roof design is very much important when deciding the number of solar panels that can be installed on the roof and the solar panel production.
Is your roof direction suitable to install solar?
Your roof direction decides the direction that your panels face. The direction of the panels decides how much time of the day that your panels receive sunlight. This greatly affects the output of your solar system.
If you live in the southern hemisphere the optimum direction for your panels is north. When your panels are placed like this, they face the longest axis from east to west so the amount of sunlight receives increases.
If you live in the northern hemisphere the optimum direction for your panels is south. When your panels are placed like this, they face the longest axis from east to west so the amount of sunlight receives increases.
How your roof pitch affects solar panel installation?
The roof of your pitch is simply the steepness of your roof. This pitch is usually expressed as a ratio between the numbers of inches the roof vertically rises to the inches it extends horizontally.
The number of inches that extend horizontally is called a horizontal run. This number is 12 in the USA. So if a roof vertically rises 7 inches for every 12 inches of horizontal run the pitch is 7 in 12 or 7/12.
You can find the pitch from degrees by using simple mathematical expressions if you know the pitch as a ratio.
The pitch angle between 300 (7/12) – 450 (12/12) is ideal for solar panel installation.
How shade affects solar panel installation?
Even though you have carefully considered all the above factors if your roof is shaded that means your solar panels do not receive enough sunlight.
Solar panels can be shaded by other structures on the roof such as chimneys, skylights, air conditioning vents, etc., or by any other external structures or tall trees.
So before installing solar panels you have to make sure that there are fewer overhead structures that can shade your panels.
Also, when talking about shading you have to keep in mind sun is not at the same level throughout the year. It goes lower during the winter season. So there will not be many sun hours during this season.
When installing a solar system you have to make sure that your roof is exposed to enough sunlight throughout the year.
Quailed professional solar providers do have tools that can estimate the production rate of your solar system according to the shading of your roof.
What can you do if your roof does not fit to install solar?
You can go for a ground solar system. The initial cost for installing a ground solar system is higher than installing a roof solar system. Also, a ground solar system needs extra land space. So if your roof does not fit to install the solar system but you have enough land, installing a ground solar system is the best option.
Also, there is a pole mounting option that requires less ground space.
When installing a solar system on the roof, there are many factors to be considered. Even though roof solar systems are more common, they might not be the best choice for you. Always try to hire a qualified, professional solar installing company to work on your project if you do not have enough knowledge about solar. Otherwise, your money and time will waste.