We often have clients tell us that they are interested in having a ground mount installed on their property. Most often it’s because of a fear of roof leaks, concerns about the structural integrity of their roof, too small of a roof to fit enough solar panels, or it could just be as simple as them “having that nice little space over in the corner of their property” that they’re not using for anything else. Whatever the reason, if its doable we’ll make it happen because 180 Solar Power is one of the premier solar ground mount installers in southern California! However, its not always doable, and/or its not always economically feasible because there are usually higher costs associated with installing a ground mount as opposed to a roof mounted system. So let’s talk about the pros and cons, and ins and outs of solar ground mounts to help you become better informed.
The best place to start when talking about ground mounts is feasibility, and feasibility is often limited by building codes. Every jurisdiction (city or county) in southern California has building codes that dictate how far a solar array must be setback from the property lines that surround the property. The codes vary by jurisdiction, and the setback requirements are usually different for the front, back and sides of the property. However, they usually range from 5 to 25 feet on each side. Additionally, there is usually a code that dictates how far from a home or business’ structural foundation the array must be setback. Because many of the properties in southern California are set on smaller land parcels, it disqualifies a good number of projects where there is not enough space to fit a ground mount after all of the setbacks are taken into consideration.
If a property is large enough to fit a solar array the next considerations are soil conditions, land contours (angle and pitch), shading obstructions, trenching distances, septic leach fields, etcetera; many of which can not only affect mechanical feasibility, but also potentially the economic feasibility of installing a ground mount. But before we get into any of that, a basic explanation should be given about how a ground mount structure is designed, erected, and secured in place, which is also regulated by building codes.
One of the first design elements that’s guided by these codes relates to wind shear, which is the amount of uplift that the wind causes on a solar array. Wind shear has a big impact on the design and construction of a ground mount structure, which is usually anchored on a two or three inch galvanized pipe frame. The higher the array is tilted off the ground the more of a sail-like affect the wind will have on the array. Therefore, the intent of the code is to make sure that the array is anchored well enough to withstand the strongest of winds, which is usually designated to be no less than 100 mph. To accomplish this, the code specifies what the depth of the post holes must be before the posts are set to depth and the holes are filled with concrete (piers). This varies based on conditions, but in general piers must be at least 12 inches in diameter, and 48 inches deep. It is also typical that piers cannot be spaced more than 7 to 9 feet apart, so it would not be unusual to have anywhere from 8 to 16 piers, or more, on a residential installation, and possibly scores or even hundreds of them on a commercial installation, depending on how large the array is. In addition to that, to get the electricity from the solar array to the property’s electric panel the conduit and wires that run from the array to the electric panel also have to be trenched and buried at a minimum depth of 18 inches. Depending on the site plan it can be a significant amount of excavation, which in turn could have a big impact on the cost of the project. Additionally, soil conditions can come into play. Excavation costs that may be reasonable for a standard clay-based soil, could soar beyond reason on a foundation that is set largely on granite or some other rocky substrate. That is not to say that it would be “mechanically” impossible to install it over a rocky substrate, but the cost could be so much higher that it could make it “economically” unfeasible to do so.
Another important code that could impact a ground mount’s feasibility is whether a property is on sewer or septic. If a property is on septic, neither the array nor the conduit can run over or through the septic system’s leach field, which sometimes disqualifies properties that would otherwise be good candidates for a ground mount.
As far as a property’s contours are concerned, we often encounter property owners who propose that an array be mounted on an excessively steep slope, or facing in a direction that would be detrimental to the power production of the solar system. If a site is excessively steep it may not be feasible because of codes relating to erosion prevention, and even if it is not subject to any such code, there could be higher costs incurred due to the added difficulty and time that may be associated with the project. Furthermore, if the only viable location on the property is on a hill that faces steeply to the north, for example, the reduced energy output of the array could render the project unfeasible because of the extraordinarily low power output and the potentially negative impact on the project’s return on investment (ROI).
Lastly, as with any solar system, shading obstructions need to be taken into consideration. If there is a tree shading the location, and it is on the property owner’s land, it’s shade can be mitigated by trimming or removing the tree. However, if the tree shade is coming from a tree located on a neighbor’s property one would need to get permission from the other property owner to trim or remove the tree. And if the shade is coming from an unalterable, unmovable object such as a neighboring building, or other structure, that too could simply render the project unfeasible.
There are other things to take into consideration that could also affect the cost of a ground mount, such as the distance from the array to the electric panel; because the longer that distance is, the more trenching that will be required, as well as possibly needing heavier gauge wire and larger conduit to counter act voltage drop. But regardless of whether or not that is the case, you can expect that the overall price of a ground mount will be higher than a roof mounted system because of the additional costs incurred for the excavation, concrete, structural materials, and labor associated with installing a ground mount.
For property owners who are interested in ground mounts because of their fear of roof leaks, it may not be an unfounded concern, depending on which solar company is hired to do the work. There is no denying that there have been horror stories about leaky roofs caused by shady fly-by-night contractors….who were also probably the lowest priced bid on the job. However, price and quality rarely go hand in hand, and most often the lowest priced product will end up having the highest cost of ownership, which could come in many forms including in the form of a leaky roof. On the other hand, if you hire an experienced licensed contractor with a strong reputation and documentable track record, like 180 Solar Power, roof leaks are not something a property owner should worry about. Having installed thousands and thousands of solar systems over the years, the 180 Solar Power team has developed well establish installation protocols to prevent roof leaks. That combined with the specialized sealants, flashings, and mounting brackets that we use allows us to offer comprehensive warranties that protect property owners against roof leaks. That is one of the reasons why the choice of which contractor to hire should be the most critical part of a property owners decision making process, and not the rock bottom lowest price.
If the concern is that a property’s roof has a more fragile lightweight or clay tile, there are installation methods and work-arounds for that, so it shouldn’t necessarily be a deterrent. For standard weight tile roofs, a property owner can expect that a handful of tiles will get cracked or broken in the installation process, but any reputable contractor will replace all cracked or broken tiles just like we do at 180 Solar Power. If the property’s roof tiles are older and are no longer being manufactured, they can still usually be sourced from businesses that specialize in selling older used tiles.
For property owners that have concern about their roof’s integrity, or its ability to support the weight of an entire solar system, it too may be a valid concern. In that case, the following things are important to know and could help make that determination. First of all, if your roof is nearing the end of its life, it should definitely be addressed. It makes no sense to install a solar system, which should have an operating life of 30 to 40 years, over a roof that will need to be replaced in the next few years. This is common sense for most property owners, but they still face the challenge of trying to figure out how to pay for the cost of a new roof. The good news is that there are many lenders that will finance a solar/roof project with zero money down, and the combined payment for the solar and roof together is often less than what the property owner is currently spending each month on their electricity bills alone. Furthermore, if in the course of installing a solar system you are going to spend thousands of extra dollars for either a new roof, or for a ground mount structure, many people find that it make more sense to get the duel benefit of investing it in a new roof rather than sinking it into a ground mount structure that still leaves you with an unaddressed roof condition. So, don’t let the fact that you need a roof replacement be a deterrent.
As far as overall weight concerns go, most solar systems will add less than 3 pounds per square foot to the roof, which is less than the maximum allowable under most circumstances. However, there are strict codes that dictate how much weight can be added to a roof by a solar system depending on the roof’s structure. Furthermore, every solar permit application must be submitted with detailed roof load calculations to show that the solar system’s weight will not exceed the capacity of the roof, and in some circumstances full engineering reports must even be submitted. Your solar contractor should be able to perform all of these calculations and manage the entire permitting process for you.
It is also worth mentioning that there are no reputable contractors that would not conduct a thorough, detailed, in-person site survey of your property as the first step of the process. Contractors that try to induce property owners to sign contracts without ever setting foot on their property are an invitation to disaster for the property owner and should be a warning to run the other way.
The goal of this article was to help bring some clarity and offer some education regarding the installation of ground mounted solar systems. As was stated in the opening paragraph, 180 Solar Power is one of the premier solar ground mount installers in southern California, we love doing them, and if a project if feasible we’ll make it happen. However, I also wanted to inform property owners that some of the reasons that they might fear installing a solar system on their roof may not be entirely valid. Also, keep in mind that this article can only offer general guidelines regarding the installation of ground mounted solar systems because every property and project is unique. Therefore, nothing in the article should be construed as a definitive assessment of your personal project. Before that can be done, a complete in-person assessment would need to be conducted by one of our technicians.
At the end of the day, whether it is installed on the ground or on the roof, solar and storage is a far better solution than continuing to pay ever increasing electricity rates to your utility company, year after year, without end. If you have more detailed questions, or would like to schedule some time with one of our licensed technicians to review a ground mount or any other type of solar and storage system for your property, call 760-264-4012 or email us at firstname.lastname@example.org. 180 Solar Power is Local, Trusted, Proven!