May 3, 2018 Solar Energy Written by Greentumble
Ground mount vs roof mount
The main component of a photovoltaic (PV) system

are solar panels, not only due to their function of converting the sunlight into electricity but also because they are a popular visual reference of any photovoltaic system. But there is also other piece of equipment that acts behind the scenes and is crucial for any solar installation. We are talking about solar mounting systems.

Mounting systems hold solar panels in place, whether it is on the rooftop or on the ground. They also provide a structural strength needed to support the natural weight of the panels, the force of the wind and in some cases the weight of the snow.

There are two main types of solar mounting structures: rooftop solar mounting and ground mounting. The decision to use one or another depends on several factors and will affect not only the final installation cost of your photovolatic system, but also the installation process and time needed to set it up.

You should, therefore, choose a mounting system that better fits your economic and technical requirements.

Advantages of ground mounted solar panels

Ground mounted solar pv systems are commonly used in large commercial or utility photovoltaic projects. However, on the residential scale, ground mounted structures can be applied as well and might come with some great benefits that roof mounted solar systems cannot provide.

Ground mounted solar panels installations consist of a metal frame that is fastened or anchored to the ground to support the weight of solar panels.

How do you know if a ground mounted solar array would suit your needs? Let’s have a look at the pros of ground mounted solar system to give you a better idea.

Solar array exposed to the Mediterranean sun

#1 Orientation and inclination variability

One of the biggest advantages of ground mounted solar systems is their maneuverability. You have several design options and you are free to decide which one suits your needs better.

In ground mounted solar panels, the tilt angle can be directly adjusted to achieve maximum possible irradiance in your location.

Solar panels will perform the best when facing South, West or Southwest, because they will receive the maximum sunlight throughout the day.

Even if the system does not face the South directly, you can easily tilt your panels to get the maximum possible sunlight.

Regarding the inclination, ground mounted panels often come with a much better range to choose from when compared to roof mounted solar panels, because they are not limited by the roof angle [1]. So, you can adjust their tilt to achieve the best energy output according to seasons, which for example allows you to prevent snow buildup on the panels in winter.

#2 Easy maintenance

Spotlessly clean solar panels will work at their maximum efficiency. Any dirt on the panels reduces efficiency and cuts into your energy savings.

One of the greatest advantages of ground mounted panels is that they can be easily cleaned by hand and regularly checked for signs of damage or other problems such as cracks or chips to the panels, loose mounting clips, damaged wiring.

Easy maintenance is one of the main factors that need to be considered when installing a solar system, especially if you are located in the Northern latitude. Because snow is a great enemy of solar efficiency, as it reduces the amount of sunlight that can reach solar panels.

Solar panel maintenance and cleaning should be executed periodically during the winter season, not only to avoid electrical losses but to prevent blocks of ice from sticking to the panels.

#3 Bigger system size

The space availability on the ground is usually larger than on the roof. That is why with ground mounted systems you can choose a larger solar installation in size and in the power output.

#4 Higher performance

Ground mounted panels offer a bigger variety of design and positioning options. These are important factors in maximizing their energy output in your location, because it allows you to adjust their positioning according to your site’s specific conditions.

Generally, power output, efficiency and performance of ground solar panels is often better than of rooftop panels [1].

#5 Safer electrical grounding system

Grounding resistance of a solar installation depends on factors such as the soil condition and the configuration selected by the solar installer.

In general, the more wire you use to conduct the current to the ground, the less effective the system is. But since ground mounted systems are already located on the ground the distance to reach the electrodes is way shorter.

So, this mounting system can protect your solar panels more effectively against any electrical fault or insulation failure.

#6 Good cooling system

Solar panel efficiency is affected by temperature changes. Efficiency drops with higher temperatures.

In warmer climates is necessary to have some cooling system that keeps panels within acceptable temperature range, especially during the summer.

The natural air flow in the ground mounted systems is the best and the most economically viable cooling system [1].

Ground mounted solar panels

#7 No modifications to the house structure are needed

One of the best features of ground mounted systems is that you do not need to make any changes to your roof or the facade of your house.

This way you avoid any possible damages to your roof (mainly due to bad installations procedures and the lack of experience from the installer’s side) [3].

#8 Visual aesthetics is not a problem

Many people do not like the fact that solar panels are visible from the front door, actually some homeowner associations do not allow the presence of solar panels visible from the street.

You can prevent this problem with the ground mounted system, because solar panels will be placed in the backyard of your house [2].

#9 Well suited for tracking systems

Installation of tracking systems in ground mounted structures is way much easier than it is for rooftop systems.

#10 Expansion

Solar rooftop systems do not leave much space for expansion considerations, but if the space in your backyard is large enough, adding extra panels to your ground system is much easier and cost effective.

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Disadvantages of ground mounted solar panels

Now, what about the disadvantages of having solar panels on the ground?

#1 Higher installation costs

Ground mounted solar systems require additional structure and materials.

To anchor the system in place, sturdy foundations are necessary. Preparation for their placement involves a structural analysis of soil and labor to prepare the area, therefore, these systems tend to be more expensive than rooftop solar mounting [2].

#2 Land use

One disadvantage is that the backyard of your house will be occupied by the panels for the next 25 years.

If your backyard is big enough that might not be such a problem, but in smaller yards, you may have only limited space for other recreational activities (barbecues, parties, gardening) left [4].

Ground-mounted solar array

#3 Safety

Given that solar panels require electrical installation and are producing electricity during the day, many homeowners are afraid that if they have kids nearby, they could either damage the solar installation or put themselves in danger.

Most solar systems are carefully grounded and protected. Equipment such as micro-inverters and wires should be well covered. However, it is possible that with time there could be some malfunction, insulation deterioration, or damage caused by weather conditions or due to the bad design and installation.

In cases like that wires could get exposed and pose a risk to other family members.

The key to avoid this problem is to make sure that your solar installer is certified and that the installation procedure follows the electrical code (this will be verified by the local utility company). You must also check your solar system for damage after any weather extremities.

#4 Shading

Shading negatively affects efficiency of your solar panels. Ground mounted systems might be exposed to additional shading due to the presence of trees or structures that your neighbors might want to add to their property.

Considering the long lifespan of solar panels (25 to 30 years), it is advisable in any case to not locate the solar system close to your neighbors’ property.

#5 Installation speed

As the ground mounted systems require additional components and considerations, the installation usually takes longer than rooftop installation does [5].

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Advantages of roof mounted solar panels

Rooftop solar systems are the most popular setups for residential installations.

Solar panels are installed on roof of your house either by the system of rails or by solar flashings (if your system is rail-less). The choice of a suitable roof mounting option depends on your budget and your roof type, as some systems are not suited for all roofs.

Either way, both of these rooftop mounting structures share similar advantages and disadvantages over the ground mounted systems. It is worth to analyze them when deciding to install a solar system.

#1 Low installation costs

Solar rooftop systems tend to be less expensive than ground mounted systems because their installation requires less labor and time to finish.

But there can be a limitation. If your roof needs to be replaced in order to be able to resist the weight of the panels over the lifetime of the solar system, then the installation costs could rise higher.

Another consideration comes regarding the lifetime of your roofing material. If the roofing material needs to be replaced sometime in the close future, the overall cost of installing solar panels on your roof could exceed the estimated budget for the project [2].

#2 Utilization of unused space

One of the best things about rooftop mounted systems is that solar panels are installed on the roof, that means in an unused space, and therefore, they will not get in the way of any of your other activities.

Rooftop solar panels

#3 Easier and faster installation

It is widely accepted by solar installers that rooftop solar panels are easier to install than panels on the ground.

It is mainly because there are less components and tools needed to complete mounting. The task can be done with less people involved, as there is no need to dig a foundation, which takes time and effort [4].

#4 Protection of your roof surface

Although solar panels are not originally intended for such purpose, their placement on your roof will protect the roofing against snow, strong winds and other objects, such as tree branches [6].

#5 Minimum shading

This advantage depends widely on the location and structures around your house.

In general, solar panels placed on the highest part of the house have lower probability to be shaded by nearby trees or buildings that would affect efficiency of the whole installation.

Unless you have chimneys, antennas, vents or other objects on the roof that might cause self-shading.

#6 Limited access to solar panels

One of the cons of solar ground mount systems is an easy access of children or unauthorized persons to them.

Placing your panels on the rooftop assures your kids will be absolutely safe and minimizes the probability of any intruder that might want to access your panels.

#7 Orientation

This advantage applies if the orientation of solar panels can be set to at least two to four different sides (front door side, back side and lateral sides). This allows the installer to select the best orientation towards South to achieve maximum solar irradiance.

If the roof only has one side suitable for the installation and it does not face the South, then it becomes a limitation instead.

#8 Aesthetics

This advantage is related to the availability of roof sides as well, because some homeowners do not like the appearance of solar panels on the front side of their house. It can be easily solved by placing the panels on the back side.

On the other hand, the presence of a photovoltaic system on the front side of your house might be viewed as a sign of being environmentally-friendly person.

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Disadvantages of roof mounted solar panels

Now what about the cons of roof mounted systems?

#1 Roof perforation

No matter what type of roof you have, it will be necessary to install the racking system or the support flashings with bolts to fasten your solar panels, and that implies that your roof needs to be perforated.

The more hole perforations your roof has, the more chances for it to fail during the lifetime of the solar system [1].

In some cases, holes will be drilled during the measuring phase, therefore, you must make sure that the installer uses some sealant to protect your roof from incoming rain or other weather conditions [6].

Solar panel attachment to the roof

#2 Structure upgrades or reparations

It can happen that the roof of your house is not suited for solar panel installation, either because of structural damage or bad design.

If that is the case, you will need to replace or repair your roof [1].

#3 System size

This probably represents the main downside of rooftop mounted systems.

The roof space (without chimneys or antennas) is usually much smaller than free space on the ground. And since the area is directly related to the maximum power that can be obtained from your solar system, roof mounted pv systems have lower maximum power limit than ground mounted systems.

That means that you may not be able to cover all your energy load. Instead, you will have to consider, based on the possible power output from your solar, which electrical devices will represent the critical loads.

Limited roof space also minimizes the possibility of expansion and upgrades in the future.

#4 Maintenance

Maintenance is essential to assure good efficiency of solar panels. The roof mounted solar systems are less accessible and their maintenance is tougher, especially during the winter season when everything is slippery.

Using hoses or water pressure to clean panels during summer months is not a good idea either, as it could cause cracks in the glass and even cancel the warranty of the system.

If your solar panels are inaccessible, you will most likely have to rely on regular cleaning and maintenance services of a professional company.

#5 Local restrictions

Sometimes homeowner associations prohibit its residents to install solar panels where visible from the street.

But if the front side of your house faces South, then this will be a problem because you will not be able to utilize your solar panels at their maximum potential.

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Which is better roof or ground mounted solar panels?

As you can see there are quite some criteria to consider when selecting the right solar mounting system for your house. And there is no magical formula to tell you which one to choose, as the decision involves individual expectations and demands that need to be discussed with your solar installer.

However, there are a few tips that might give you a better idea.

Photovoltaic solar panels on a cabin

When to choose roof mounted solar pv system?

You should select the solar rooftop option if…

  • The available space in the backyard is used for gardening, barbecues or recreational purposes and there is no other space for these activities. Would you like to lose the chance of having fun in your backyard? I don’t think so.
  • Your roof has several sides available for solar panels.
  • Your rooftop is not made of Spanish shingles.
  • You do not wish for any excavation or digging in your backyard.
  • The only space available for solar panels in your backyard is very close to the neighbors’ property.
  • Your house or roof are new or recently upgraded.
  • The available space on the roof is enough to cover your household’s energy needs.
  • The installation costs of roof mounted are lower than ground mounted.

When to choose ground mounted solar pv system?

You should select the ground mounted option if…

  • Your space in the backyard is wide and extensive.
  • The available space on the rooftop is not enough to supply the energy load that you need.
  • There are long hard winters or a lot of dust and sand in your location.
  • You think there might be space for some possible expansion of the system in the future.
  • Your roof is unsafe and after replacement costs would exceed your budget.
  • There are restrictions in your neighborhood regarding the installation of solar panels on the rooftop.
  • The overall efficiency achieved by a ground mounted system will be higher than the roof mounted due to the tilt and inclination angles.
  • You wish to install solar tracking mounts.
  • There are chimneys, antennas or vents in the rooftop that might cause shading.
 
 

References

[1] https://www.altestore.com/blog/2012/07/top-six-reasons-to-do-a-ground-mount-vs-roof-mount/
[2] https://www.solarpowerauthority.com/ground-mounted-versus-rooftop-mounted-solar-panels/
[3] https://www.finder.com.au/benefits-of-ground-mounted-solar-panels
[4] https://www.spectrum.solar/uncategorized/ground-mounted-solar-vs-rooftop-solar/
[5] http://statkraftblp.com/ground-mounted-vs-roof-top-reality-check/
[6] https://www.youtube.com/watch?v=hkT2fVZ9C5g