For people living in cities, rooftop solar - literally putting solar panels on top of your house - is by far the most popular choice when going solar. For many people, it’s the only option, because city lots are often too small to consider anything else.
But for people living on larger suburban lots or in the country, ground mounted solar can be an option and, in fact, is often the better way to go.
Ground mounted solar is exactly what it sounds like: it’s a solar panel racking system that is installed into the ground.
There are different types of mounts, as well as add-ons such single or double-axis trackers. This article will discuss the pros and cons of ground mounted solar, and the different types of equipment available.
There are a lot of manufacturers that supply solar ground mounting systems, so they all look a little different. However, there are two major kinds of systems that you’ll encounter.
This type of ground mount is a scaffolding onto which rows of solar panels are mounted. These are fixed-tilt, which means that the angle of the solar panels can’t be changed. They’re usually made of steel, aluminium, or a combination of both.
As you can see in the photo above, this is a scaffolding-type structure that is anchored into the ground. The type of foundation required depends on the soil, which is typically assessed by a geotechnical engineer.
This type of mount uses one or more poles to support of a group of panels. A single pole might be used to support just one panel, or a small grouping of panels. It can also be extend to use many poles for very large systems.
One advantage of pole mounts is they can be used to incorporate sun trackers, which are motorized systems that automatically orient the panels to face the sun throughout the day, allowing them to harvest more energy. A single pole mount may use a dual-axis tracker, which can move the panels both up or down and side-to-side, or a single-axis tracker, which moves only up and down.
Multi-pole mounts may use only single-axis trackers. Even though single-axis trackers don’t have a horizontal movement, the ability to track the sun as it moves higher and lower in the sky throughout the day does allow the panels to capture more sunlight than a static mount.
While sun trackers do allow solar arrays to harvest more electricity with fewer panels, they have the disadvantage of additional mechanical complexity, increased maintenance, and the possibility of component failure.
Because of this, the additional cost may not be worth it for residential-scale solar installations. However, if you only have a small footprint for solar panels and want to generate the maximum electricity possible, a tracker might make sense. A professional solar installer will be able to do a cost-benefit analysis based on the specifics of your location.
If you have a large yard that doesn’t have shade from trees or buildings during the day, ground mounted solar might be an option for you. In fact, it’s often the better option. Here’s a summary of the pros and cons of ground mounted solar:
You don’t need to worry about the condition of your roof
Easier maintenance and repairs
Can be lower cost in the long run
Gives you the option of sun trackers
Easier expansion in the future
Can be incorporated into creative designs
Usually higher upfront cost
Requires unshaded yard space
Not suited for all soil types
At a quick glance, you can see that there are more pros than cons. In fact, if you have an analysis by a professional solar installer telling you that ground mounted solar will work in your yard, I would generally recommend that you go for it. Here’s an in-depth discussion of each of the pros and cons.
When you have rooftop solar, the panels are installed onto a racking system that is attached to your building. Adding and removing panels isn’t work that most homeowners should perform themselves. Instead, you will need to hire a professional solar installer (usually the same who did the original installation in order to preserve the warranty).
This means that if you ever need roof repairs performed underneath the panels, or have a complete roof replacement done, you will need to pay an installer for two visits: one to remove and store the panels, and then a second to reinstall the system after the roofing work is done.
The price for this work will vary a lot depending on the specifics of your installation, but you should plan for the cost to reach as high as a couple thousand dollars.
That’s why it’s recommended to only install solar panels on a roof that has plenty of life left. I would recommended a minimum of 15 years. If your roof needs a replacement or requires maintenance before your solar panels reach the end of their life (which can be more than 25 years), you’ll have a big added cost for the solar removal and reinstallation.
None of that matters with a ground mounted system, which uses a freestanding structure that is separate from your home. Of all the reasons to consider ground mounted solar, this is probably the biggest.
While solar arrays normally need very little maintenance, having your equipment at ground level does make both maintenance and repairs a lot easier.
Repairs are the bigger concern. While solar panels have no moving parts and can be expected to last 25 years or more, they do occasionally fail. In addition, there are other components on a solar array to worry about, such as microinverters or power optimizers.
Like panels, solar inverter components have no moving parts and typically have warranties that last from 10 to 25 years. String inverters are mounted near your electric panel, but microinverters and power optimizers are mounted on the backside of each solar panel.
Enphase, which manufactures the most popular microinverters on the market, includes a 25 year warranty with its products. While failures of their newer products are rare, they can happen.
Finally, critters often like to nest in the space between solar panels and a roof. This can be a real problem if the critter is a squirrel, because squirrels really like to chew on wires.
If you need a repair to your rooftop solar panels, whether it’s because of a failed component or a pesky rodent, it will often require a solar installer to come with a bucket truck to be able to remove the panels so they locate the failure, and then to lift any replacement panels back up to the roof. This can get expensive, because if an equipment failure is covered by a warranty, most warranties do not include labor (LG and SunPower are the notable exceptions).
However, if you’ve got a ground mount, everything is a whole lot easier. In fact, if you’re confident about working with electrical equipment, some equipment replacements can be performed by the homeowner (although I don’t recommend it if your system is still covered by the installer’s labor warranty, because you could void the warranty).
Having a ground mount also makes it a lot easier to inspect wiring for critter damage, and to periodically clean your solar panels. It’s usually not worth the risk of getting on a tall ladder to clean a rooftop solar array, but if you have a ground mount that you can easily wipe down with a squeegee or brush the snow off of, that’s definitely another big advantage of a ground mount.
The upfront cost of a ground mount is usually higher because of the material costs of a ground mount are higher, the need for ground preparation and foundation work, and the need for a geotechnical inspection of the site.
However, in the long run, you could save money with a ground mount because of easier maintenance and repairs. Also, it’s easier to expand a ground-mounted solar array in the future.
It might not be on your radar now, but electric cars are rapidly growing in popularity. Also, more and more homeowners are switching away from fossil fuels to all-electric homes with the use of appliances like induction cooktops and heat pumps.
If you decide in the future to electrify more of your home, having a ground mount will make it easier to expand your solar array to meet your increased energy usage.
A sun tracker is a motorized device that will automatically tilt your solar array in either one or two axes to follow the sun as it moves through the sky during the day. By keeping panels perpendicular to the sun, a sun tracker can increase the energy harvest of an array by around 25%.
But trackers aren’t an option with a rooftop array. So, if you want your array to generate the maximum power possible, going with a ground mount opens up the possibility of using either single or dual-axis trackers.
Most ground mounted solar installations are entirely utilitarian in design because commercial and utility-scale are the largest customers of this equipment.
However, homeowners don’t have to use off-the-shelf equipment. If you’re willing to get creative, solar panels can be integrated into unique architectural structures that generate electricity and serve as shelter, such as a gazebo or carport.
For some examples, take a look at my article with seven different creative uses of solar panels.
Like other ground mounted arrays, most of these designs have the advantage of being more accessible than a rooftop installation, which lowers the cost of future maintenance and repairs.
While ground mounted solar generally has more advantages than disadvantages, there are some drawbacks. I’ve already mentioned the higher upfront cost, but there are a couple other considerations to weigh.
Just like with a rooftop installation, any shade on your installation site can have a dramatic effect on how much electricity you can produce. If you’re thinking about going with a ground mount, take a look at your yard and make sure that there is no shade from trees, especially in the middle of the day. Late day or early morning sun will have less of an impact, but the middle hours of the day are when you will generate most of your electricity.
If you have trees throwing shade on your site during those times, see if you can trim them back or even have the trees removed.
While it might seem environmentally counterproductive to cut down trees for a solar array, the fact is that the carbon offset of operating a solar array will far outweigh the carbon impact of cutting down a tree or two.
According to the EPA, growing one tree for 10 years will offset the greenhouse gases from 85 kilowatt hours of electricity from utility power plants, on average. Most home solar arrays, even smaller ones, will probably generate that much in just one week, if not much more. Check out the EPA greenhouse gas calculator to do your own analysis.
A ground mounted solar installation with its scaffolding, racking, and solar panels weighs thousands of pound. In addition, the array must be able to withstand severe winds, which means the foundation must not only be able to carry the weight of the equipment plus any snow that could accumulate on top, but also be able to prevent the array from lifting up in gale force (or higher) winds due to air pressure on the backside of the panels.
This means that you will need a proper foundation and soil type to support it, requiring a visit from a geotechnical engineer to assess the site and design an appropriate foundation.
The best type of soil is well-drained, compacted soil. Certain soil types will be problematic, such as clays or loosely consolidated sand or silt. If you have ground that frequently floods, a high water table, soil that experiences frost heave, or is in a location that experiences landslides, you may require additional engineering work to make the site suitable, which could make the cost prohibitive.
As you can see, while there are some drawbacks to a ground mounted array, if you have a suitable location for it, there are a lot of reasons why a homeowner would prefer to place solar panels in a yard rather than rooftop.
Making a fair assessment of the different options is something that a qualified solar installer will help you with. To find one in your area, use the links below.