Ground-Mounted Solar Panels: What Installers Need To Know
Do you have potential solar customers who don’t have a home with optimal solar potential? For example, perhaps their roof is shaded, or it lacks a southern orientation. Are there dormers or skylights that limit their options or the size of the PV system? Does the roof have structural issues that make a rooftop installation questionable?
A ground-mounted solar system is often an excellent solution because it allows you to place the solar panels in the sunniest spot on the property. Clients may inquire if it is an option to install solar panels on the ground or if it is cheaper. If you don't already offer this mounting solution, it might be a great addition.
Offering ground mounts may increase your pool of potential solar energy customers and result in more satisfied customers. Sometimes, it can boost the output of the solar energy system, therefore boosting the return on investment. Some homeowners might want a solar tracking system on their array to increase energy production, making a ground mount essential. Unfortunately, ground mounts are often more complicated to engineer and install, especially for specific soil types.
What Are Ground-Mounted Solar Panels?
Ground-mounted solar power systems offer design freedom. Instead of only mounting the panels on the house or garage roof, there are expanded options. The bigger the property, the greater the possibilities. Larger rural properties and farms are ideal for ground mounts, but some suburban and urban sites are also suitable.
Sometimes, solar installers can add PV panels to a structure in the yard, such as a trellis or carport. These structures can serve dual purposes and result in very efficient use of limited space. For example, a trellis can provide shade and is ideal on the south side of the home. For solar carports, the PV modules can shade and protect a vehicle from the elements.
The Two Types Of Ground-Mounted Systems
Ground-mount systems come in two primary designs: with standard-mounted panels or with pole-mounted panels. We’ll go over both options.
Standard-Mounted Panels
This approach uses ground anchors to hold the metal framing in place with rails. The solar panels are then mounted, typically at a fixed angle.
The configuration and layout of the metal framing will vary by the racking system and desired design. If the array has more than one row, it is helpful to prevent shading from the first row to the second and allow enough space to enable mowing if needed.
It is critical to select the best orientation and angle to meet the energy goals of the customer. Some of these systems are manually adjustable, which will require additional maintenance. It’s not critical to seasonally adjust systems, even if the racking system has the capability, but it will result in slightly less energy production.
Pole-Mounted Panels
Renewable energy contractors mount these solar systems on one or two central poles that are driven into the ground. These installations are usually taller than standard-mounted panels and can have greater permitting requirements due to maximum wind load and soil composition considerations.
Often, pole-mounted systems have a single- or dual-axis tracking device that follows the sun for increased energy production. However, because it is a mechanical system with moving parts, tracking systems sometimes fail or need maintenance. If you install a tracker, conduct research to ensure the manufacturer is known for reliable equipment and provides strong warranties.
If the system is seasonally adjustable, ensure the customer understands the maintenance requirements of manually adjusting the panels to increase electricity production. Solar trackers have become more reliable over the years, but are not right for every client or solar site.
Ground-Mounted Solar Panel Installation
Installing these arrays varies widely by the racking system, anchoring approach, property layout, climate and soil type. Regardless, adequate planning in the project's design phase helps prevent issues with permitting, the installation process and interconnection. Engineering expertise is critical for successful projects.
Installing Standard-Mounted Panels
There are a variety of ways to secure standard-mounted panels. Concrete piers are the most common, but concrete ballasts, helical piles and driven piers can be used as well. In some cases, the best option depends on the available equipment, maximum wind loads, and soil type. Also, your clients may have a preference because some options have a greater long-term impact than others.
Some local ordinances will require a security fence around the solar array, increasing the cost, labor, and materials needed to complete the project. Also, plan accordingly for the fence to prevent it from shading the panels or to make it difficult to mow around the photovoltaic solar panels and perform maintenance.
Installing Pole-Mounted Panels
Installing a pole mount will require completing some site work and may have more stringent permitting requirements. In some jurisdictions, an engineer must specify the foundation details, taking into account soil composition and maximum wind loads. Typically, a tractor-mounted auger is the best equipment for digging the narrow hole needed, but they might not perform well in rocky soil. The given racking system will have a maximum number of panels, which varies by model.
Pros And Cons Of Ground-Mounted Solar Panels
There are some major benefits and drawbacks for ground-mounting PV panels:
Pros
No drilling into the roof: Some potential customers are very concerned about creating roof penetrations. Perhaps this could void their roof warranty, or they are worried about roof leaks. One big plus to ground-mounted systems is that they require no drilling on your roof and, therefore, no roof penetrations.
Potentially more efficient: If the roof does not have a good solar resource, solar panels might generate moderately or significantly more energy as a ground-mounted system. In this case, it might result in a higher return on investment and be more cost effective, depending on how much the ground-mount increased the total system cost. Also, installing a single- or dual-axis tracker can boost solar production.
Seasonally adjustable: Some ground-mounted systems can be manually adjusted. This means that the panels can be at a steeper angle in the winter because the sun is lower in the sky. The panels can be at a gentler angle during the summer because the sun is higher in the sky. Seasonal adjustments can modestly increase the total solar electricity generation.
Reduce rapid shutdown requirements: The 2017 National Electrical Code has requirements that dictate when rapid shutdown on each panel is required to reduce the shock potential to first responders. Typically, ground mount systems do not need to meet the same rapid shutdown requirements, but interpretation of the laws can vary by region, the layout of the ground mount, and the location of the balance of system.
Cons
Additional cost: Often, ground-mounted systems have a higher upfront cost. This is because of the additional racking, permitting and installation costs. Digging holes can require special equipment and even meeting engineering requirements to determine maximum wind loads and soil types. In some cases, the racking system does provide an additional benefit, though, like a solar carport.
Takes up yard space: Typically, ground-mounted systems occupy more space than mounting the solar PV modules on the roof unless the installer incorporates it with a useful structure, like a trellis.
Vegetation control: To prevent shading of the solar panels, it is still critical to control vegetation. For example, it is not recommended to plant trees or allow tall vegetation on the south side of the solar panels because this will decrease solar energy production. Even tall grass can hinder total system output.
Rooftop Solar Panels Vs. Ground-Mounted: Which Is Right For You?
Solar companies can provide critical information to help solar shoppers make informed decisions. Explaining the pros and cons of ground mounts and determining if your client will benefit from this mounting option is critical.
Don’t let design and engineering hurdles deter you from installing ground mounts. GreenLancer's network of design and engineering professionals are specialists in all types of solar projects, including ground-mount design. Connect with a rep today!