Rooftop vs ground mounted solar: pros and cons
Most homeowners put their solar panels on the roof, but if you have room in your yard, ground mounted solar can be a better option.
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. Because the system gives the owner more freedom about where to point their solar panels, a ground mounted system can generate more power and give you more freedom to locate your system.
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.
What does ground mounted solar look like?
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.
Rooftop vs ground mount solar
Only around 3% of home solar systems are installed on ground mounts. Most homeowners go with a roof mount, and it’s probably the best choice for you too.
However, there are some cases where a ground mount is the better option. For example, if your roof is old but you want solar installed soon (perhaps to advantage of a solar rebate) a ground mount can mean not having your solar installation delayed by a roof replacement project.
Here’s a summary of the pros and cons of ground mounted solar:
As you can see, the list of pros is longer than the cons, making it seem at first that ground mounted is the better way to go. However, this doesn’t reflect the fact that the cost differential can be steep, putting ground mounted solar out of reach.
In spite of that cost, it’s possible that the pros will, over the estimated 25 year lifespan of your system, result in a net cost savings over roof mounted panels.
Here’s an in-depth explanation of the pros and cons.
Pro: You don’t have to worry about your roof with ground mounts
When you have rooftop solar, the panels are installed onto a racking system that is attached to your building. If the roof underneath needs repairs, the panels would have to be removed, which 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 or a complete roof replacement, you will 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 be in the neighborhood of 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.
Pro: Solar panels near the ground are easier to clean and repair
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.
All of this is easier with ground mounts. 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.
Pro: Ground mounts can be lower cost in the long run
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 homeowners are switching away from fossil fuels to all-electric homes with things 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.
Pro: Sun trackers are an option with ground mounts
A sun tracker is a motorized device that will automatically tilt your solar array in one or two axes to follow the sun as it moves through the sky during the day. By keeping the 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.
Pro: Creative ground mounted designs are possible
Most ground mounted solar installations are utilitarian in design, but 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.
Disadvantages of ground mounted solar
While ground mounted solar has many benefits, there are drawbacks too. I’ve already mentioned the higher upfront cost, but there are other considerations to weigh.
Con: Ground mounts require unshaded yard space
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.
Con: Ground mounts require suitable soil and a foundation
A ground mounted solar installation with its scaffolding, racking, and solar panels weighs thousands of pounds. 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 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.
Conclusion: work with a qualified installer to help you choose between ground and roof mounted solar
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.