Pole Mounted vs Roof MountedBlogRenewable Energy
Par Clément Benoit
There are a couple common types of installation methods for solar panels here at Volts Energies. Most of solar installations made by Volts Energies are pole mounted.Indeed, many off grid sites (our main market) such as chalets, forest camps, outfitters etc. are located in woody locations, with a higher tree density than in urban areas, and more probability that a building roof does not feature optimum conditions for the solar panel production. Then the pole mounted option allows for more flexibility on the choice of the optimum area so the solar panels can achieve the best power production performance. Another key consideration with the pole mounted option is an easier access to the solar panels to clear off the snow accumulation in winter. And a pole mounted system designed with a manually-changeable solar panel slope helps in this context.
Our roof mounted solar installations typically occur in outfitter projects where there is an existing building such as a reception building, featuring a larger roof area and more suitable orientation conditions than other the lodges of the site to install solar panels. Depending on the project, pole-mounted can also be combined with a roof mounted for different reasons (available space area, site conditions etc.). One consideration can also be the roof slope (often ~20 to 30°) which set once and for all, then not optimum for a solar production during the winter season where ~60° is recommended (Southern Quebec).
Let’s examine different advantages and disadvantages of both installation types when considering solar. The goal of this blog post is to highlight the advantages and disadvantages so you can make the most informed decision for you.
First, let’s first define what a ground mount and roof mount solar system is.
Roof Mounted Solar Panels
In Quebec, rooftop installation is common in residential or commercial grid-tied systems (more in urban areas with lower tree densities), although there are also some in off-grid sites. This type of installation consists of a generally aluminum racks, which hold the panels in place, fixed directly to the roof. Panels can be attached to flat or sloped roofs made of metal, shingles or rubber.
Figure 1: Example of pole-mounted installation.
Here 8 solar panels of 265Wp (2120Wp total) used with a 48VDC battery bank of 18kWh and a 4 kW inverter-charger
Pole Mounted Solar Panels
A pole mount is when the panels are secured to a rack structure with steel beams and mounted on a pole incurring a concrete foundation buried in the ground.
Ground mounts can be installed wherever the conditions are best for solar, making them a great alternative for someone who doesn’t have enough usable roof space or suitable conditions for solar, or just prefer to not have panels mounted to the roof.
Figure 2: Example of pole-mounted installation.
Here 6 PVs of 285Wc (1710Wp total) used with a 24VDC battery bank of 16kWh and a 3 kW inverter-charger.
Roof Mounts: Pros and Cons
- Roof mounts utilize space that otherwise wouldn’t be used.
- Typically, the installation cost is lower compared to a pole mounted system
- Doesn’t take up land that could be utilized for other activities
- Limits unauthorized visitors from accessing the panels
- Roof penetration is required for shingle roofs
- Could require a new roof before installation
- Will make future roof maintenance more difficult
- Adds weight to your roof, and in some cases, the roof could require additional support mechanisms
- Can be a safety hazard for the installation team
Things to consider:
- The age and condition of your roof
- If your roof is south oriented (at least mostly) and free of shading sources for a solar panel area that will fit your energy needs
- The impact solar could potentially have on your roof warranty
Pole Mounts: Pros and Cons
- Pole mounts can be installed in any direction or location, positioning them for optimal energy production
- They can be installed at multiple angles
- The system can easily be accessed for maintenance
- They fit in applications where bi-facial solar panels are used. Indeed, bi facial solar panels can produce up to 30% their nominal power (in best test conditions) from the environment solar irradiation reflection on the panel rear. A good strategy not only for the extra production, but also when the solar panels front is covered of snow. In this situation, the panel rear face production will bring some heat to the panel front face, resulting from the rear production, and then will favorize self snow clearing off.
Figure 3: Example of pole-mounted installation with bifacial solar panels.
Here 8 solar panels of 390Wc (3120Wp total, up to 4000Wp with bifacial gain) used with a 48VDC battery bank of 38kWh and a 6 kW inverter-charger.
- Typically, the installation cost is higher.
- Takes up large land areas when several required (commercial scale)
- Easier access for unauthorized visitors
- Likely requires using a pole with sufficient height to avoid snow accumulation in winter that may occur shading from the lower part of the solar array
Things to consider:
- Pole height accordingly to the sources of shadings surrounding the area chosen to install the solar panels
- Racking design according to the wind conditions (heavy duty type or not)
- Ground conditions to make appropriated concrete base and pole design