CONCRETE CONSTRUCTION FOR SOLAR ENERGY
Despite what you may have read in the media recently, the solar power industry in the United States is still expanding. Recent studies show that the solar industry has already added 260,000 jobs to the American economy, more than any other industry in recent years. That number will only grow as technology improves, demand increases and the price of solar panels continues to drop over the next few years.
More and more businesses and homeowners are realizing just how economical solar power can be. Even Kentucky’s Coal Museum, dedicated to spreading the word of how great coal is, uses solar power as a source of affordable energy.
Even now there are ways that you can cut costs on the installation of solar power for your home or business. One of the best ways that you can do that is by using concrete to provide ballast for solar arrays on a rooftop or on the ground.
As a homeowner, you may have hesitated about installing a solar panel array on your rooftop because in the past most solar panel arrays had to be attached to your house’s rafters, which meant drilling holes in the roof. While installers always take care to ensure that these holes are properly sealed, they can cause issues later on, especially if you have a flat or low-sloped roof. Over time, rain or snow would find a way to leak inside.
Another place where building a solar array can be problematic is on top of a former landfill site. Many communities use these locations to build solar arrays. The problem is that you cannot penetrate the liner that covers the landfill beneath.
The solution in both these cases is solar ballast made with concrete.
Just a note — you may occasionally see the term “solar concrete” referring to something other than solar ballast. There is a type of concrete used to produce solar energy, but that is a subject for another article.
HOW DOES SOLAR BALLAST WORK?
Solar ballast depends upon concrete blocks. These blocks are located throughout a solar array to secure it to the roof or to the ground. This prevents wind lift or shifting of the array and means that you do not have to penetrate the roof or the ground.
So how do you determine how much ballast a solar array needs?
There are several determining factors:
- The size and arrangement of the solar array itself.
- The location of the solar array. This includes determining factors like wind and any possible seismic activity.
- The shape of the roof. Is it a flat roof? Is it low sloped? How much of an angle do you have to work with?
- What type of racking will be used on the array?
- What are the height and the strength of that racking?
- The code requirements in each jurisdiction. Different locales often operate under different solar code requirements.
- The best person to determine the amount of ballast needed is a licensed structural engineering professional engineer. Many racking companies have a professional engineer on staff, but if they don’t, you can hire a professional engineering consultant who can make the appropriate calculations.
WHAT ABOUT BALLAST ON OLDER BUILDINGS?
If you’re going to build a solar array on top of a commercial building or the roof of a home, it isn’t necessarily any more difficult than building an array on the ground on top of a landfill or some other site. But there are factors that you need to consider with the building’s roof that you don’t need to consider on the ground:
- The roof’s warranty. The ground doesn’t have a warranty. But roofs do and anything that you build on a roof has to be done with the warranty in mind.
- The age of the building.
- Seismic activity area.
Interestingly, older buildings are probably better prepared to accept a solar array system using concrete ballast. Buildings constructed in the 1950s, ’60s or ’70s feature steel truss structures better equipped to deal with arrays and ballast. Engineers are more concerned with buildings that are 15 to 20 years old. In those years, building codes changed and companies built roofs that would hold only minimum loads. In news stories about roofs that have collapsed because of snow or some other factor, they are frequently roofs that were built during this time. These roofs are not good candidates for solar arrays.
Companies eventually realized the problems they were creating for themselves and made changes so buildings that are five to 10 years old, for instance, are better able to deal with the weight of a solar array. As well, as we will explain below, technology has shown that less ballast is needed than previously thought to hold a solar array in place.
TECHNOLOGY AND SOLAR BALLAST
Technology has created even more reasons for using concrete solar ballast. Using wind tunnel analysis, and improving the way that solar panels interconnect, engineers determined that you could use less ballast. Improving the way the panels were interconnected led to improvement in load sharing. Also, when racking companies include wind deflectors on their arrays, the arrays become more aerodynamic.
Why is less ballast important? Many homeowners and commercial building owners worry about having concrete slabs on the roof. They worry about how much weight is on the roof. But knowing that you need less ballast to keep the arrays in place makes homeowners more comfortable with using concrete slabs to secure their solar arrays.
While it is true that you can purchase rectangular-shaped concrete blocks at your local home improvement store, concrete manufacturing companies create specially designed concrete ballast for solar arrays.
For instance, communities near Annapolis, Md., wanted to build a solar array on top of a landfill site. State law, however, said that the landfill site could not be disturbed so that meant builders could not use an auger to dig holes to anchor the array. Instead, engineers working with a concrete company came up with a unique solution.
The company built concrete ballast slabs with special grooves. These grooves allowed the builders to lay the cables that would carry the power to the main grid. The design also included spaces for a copper ground loop and other wiring skids. Because pre-cast concrete was used, the builders were able to complete the project much more quickly and save money in the end.
Utility companies also work with concrete companies that do precasting because precasting is an even more efficient method than cast-in-place construction. Engineers and designers can work together to create customized concrete blocks and pads to use on ground sites, such as former landfill sites or areas where the ground is too soft to use a penetration method.
WHAT ARE THE ADVANTAGES AND DISADVANTAGES OF USING CONCRETE SOLAR BALLAST?
There are two main advantages of using concrete solar ballast — cost and speed.
While there is some debate about which system is more cost-effective, solar ballast or roof penetration, there is no debate that the labor costs of solar ballast are much lower. This is especially true if you work with an experienced installer.
Ballast costs less than roof penetration because installation happens faster. Again, when you work with an experienced installer, it takes them less time to build an array, which not only means you save money but also you can start using solar power much sooner.
The season you install your solar array also favors concrete ballast. While either system can be installed in the summertime, it’s much more difficult to install a roof penetration system in the winter. Concrete ballast, however, can be installed at any time of the year.
There are two main disadvantages of using solar ballast — weight and breakdown of concrete.
As we noted above, commercial roofs constructed during the ’80s and ’90s may not be suitable for solar panels using solar ballast because the roof just won’t bear the weight of the concrete. Yet as we also noted above, technology has led to improvements in the way that solar panel arrays are constructed which means that they require less ballast and thus you can build a solar array with a smaller load.
2. BREAKDOWN OF CONCRETE
Exposure to wind, rain, UV light, freezing and thawing — especially if you live in a colder climate — wears down concrete, and that concrete can wear down even faster if you bought it at your local home improvement store. Broken or cracked ballast segments can fall from the racking onto the roof. This means that the ballast is no longer doing its job of holding the array in place. And a piece of broken concrete might tear or damage the membrane of the roof.
That’s why it’s important to use concrete that has been rated for the environmental conditions frequently seen in your area. Concrete will perform better and last longer if you use the appropriate quality level. Before you select concrete ballast for your solar array, do a little homework and talk to local concrete companies about their experience with the appropriate rating and quality for concrete in your area.
USING CONCRETE BALLAST FOR GROUND MOUNTS
While concrete ballasts are ideal for flat or low-sloped roofs, they are also an effective solution for ground mounted systems. As we noted above, landfills which have been sealed off are an ideal place to use concrete ballast. More communities choose former landfill sites to build solar power arrays these days because nothing else can be built on the site. Solar arrays built on landfill sites provide communities with a way to generate renewable energy while using land unavailable for other purposes.
Concrete ballast also works very well in areas that are too moist or wet for ground penetration to work effectively. Corporate ballast also works in “brownfields” — areas that contain contaminated soil. You don’t want to disturb the contaminated soil, so concrete ballast is the best answer.
Finally, solar displays that are planned for rocky areas also benefit from the use of concrete ballast. You can try to drive posts into the ground in rocky areas, but there’s a better than even chance you’re going to hit a rock beneath the surface.
Ballast ground mounts can be more expensive than penetration systems, but once again, what you save in labor costs makes the two systems financially comparable.
EVEN HOGWARTS USES CONCRETE BALLAST TO MAINTAIN IT SOLAR ARRAYS
Well, it’s not exactly Hogwarts, but Gloucester Cathedral in Gloucestershire, England, was depicted as Hogwarts in several of the Harry Potter films. The cathedral, built in the seventh century, recently installed a solar array on its roof using concrete ballast to hold the array in place because the guardians of the cathedral did not want to penetrate the roof. Working with a local concrete company, the solar installers designed a unique system to hide the concrete ballast, so it did not obscure any views of the church.
While the story is interesting on one level because of its connection to the Harry Potter films, for our purposes it illustrates how concrete ballast can be used in the most extraordinary places to ensure that solar arrays remain in place without having to penetrate roofs. Even ancient ones.
Whether you have a commercial building with a flat top roof, a home with a flat or sloping roof, or even a roof on a historic building, if you want to install solar arrays to generate renewable energy, concrete ballasts are the choice to make. Easy to install, cost-effective and durable, concrete ballast means deploying solar power for your home or business is much more within your grasp.
LET R. J. POTTEIGER CONSTRUCTION SERVICES, INC., SUPPLY YOUR CONCRETE NEEDS FOR YOUR SOLAR ARRAYS
At R. J. Potteiger Construction Services, Inc., we’ve been in the business of providing great service to our customers for over 20 years. We work hard to be more than just the contractor for clients. We want to be their strategic partner and their advocate. We work hard as a team to give our customers innovative and imaginative solutions that fit their expectations and individual requests. We know how important it is to finish a project within a budget and a schedule.
If you need concrete structures or ballast for your solar displays, let us show you how we can provide what you need on time and on budget. You can call us at 1-717-697-3192 or contact us online to leave us details about ways that we can work together to make your solar project a reality. A member of our team will get back to you as soon as possible.