A Brief Exploration of Helical Pile Foundations

Helical piles are a type of deep foundation that "screw" into the ground, instead of being excavated or driven. Passing through loose, saturated, or poorly-consolidated soils they can find bearing in firm and supportive layers, leveraging the unique power of a helix plate.

They were invented in the early 18030's by an Irish engineer named Alexander Mitchell. Initially, he intended them to be used as foundations for lighthouses, bridges, and piers. Today however, helical piles have proven themselves as a sturdy solution for all types of residential and commercial construction projects.

Let's take a look at how a helical pile works and their unique method of installation.

How Does A Helical Pile Work?

How Is A Helical Pile Installed?

Installing a helical pile foundation for solar panels is quick, easy, and demands a minimal amount of site preparation.

No excavation is needed to install a helical pile, unless the pile top must sit below grade. This greatly simplifies the installation of solar panels and reduces environmental impacts, as there's no requirement for extensive earthwork or disruption.

To provide the rotational energy that will rotate each pile into the ground, we use a hydraulic drive head. It's used to deliver steady, reliable, high-torque power that firmly anchors the foundation.

Speaking of torque, that's an importance aspect (and benefit) of helical piles.

By reading the torque we're exerting on the piles during installation, we can calculate their ultimate load capacity. Thanks to an established empirical relationship between installation torque and load capacity, you enjoy real-time quality control that ensures a successful result.

Monitoring installation torque also enables us to identify unexpected or unidentified ground conditions, allowing for a quick and effective response to unwanted surprises.

Once the piles are installed, they can be trimmed to the appropriate elevation and adapters attached to the tops. They're now ready to support a solar panel array!

Why Use A Helical Pile Foundation For Solar Projects?

At this point you might be thinking, "This is all well and good, but why would I want to use helical piles instead of another solution for my solar panels?"

Great question! After all, it wouldn't be very reassuring if we simply told you to "trust us" when it comes to your solar energy foundation.

Instead, we're going to walk through some of the key reasons you should consider a helical pile foundation solution. We can't cover all of them in this article, but these will give you a clear idea of the main benefits you could expect to see.

Quick & Easy Installation

Perhaps the most significant benefit of using helical piles for your solar energy project is the sheer speed and ease they deliver.

As you already saw, the installation process for a helical foundation is swift and hassle-free owing to the "screw in" nature of the technology. This dramatically reduces construction timelines compared to solutions like concrete, while minimizing disruption to your site.

In fact, when stacked against poured concrete, a helical foundation can be installed and ready to use over 180% faster. With the growing demand for solar energy, saving valuable time on construction allows you to finish sooner and get those panels pumping out clean power.

If you're a homeowner, it means you can start enjoying your solar investment in less time. For solar energy companies and contractors, you're able to get more projects done and increase revenue without expanding your team.

High Performance in Central New York Soils

We face an array of soil conditions here in Central New York, from soft shorelines to packed clay and everything in between. Coupled with our (typically) damp climate that brings large amounts of rain and snow, and you have a recipe for foundation frustration.
In order to overcome these challenging conditions, you need a foundation which readily adapts to a range of soils and locations. Especially considering the fact that are often built in areas with less-then-ideal ground compositions.
Because of the helix plate design of a helical pile, it offers serious load capacity even in poorly-consolidated soils with low bearing. As the helix plate creates a large surface area underground, the pressure of surrounding soil on the top and bottom prevents movement.
Importantly, the helix plate resists movement in both compression and tension meaning it won't sink down or pull out of the ground. This is crucial for solar panels as they often face substantial "pull out" (upwards) forces as winds blow underneath them.
In fact, a little anecdote from a fellow foundation company in Canada describes how a solar panel they mounted on helical piles actually survived an F1 tornado that damaged nearby buildings!

Reduced Environmental Impact

The whole idea of solar energy is to reduce, and eventually eliminate, using fossil fuels for energy generation. How long it takes to reach that goal remains to be seen, but it's important to remember there's still environmental costs associated with solar energy construction.

A big part of that environmental impact comes from the materials used to build, and support, those solar panels.

We can't do anything about what goes into the panels themselves, but we certainly can do something about the foundation.

Reality is that concrete, while a versatile and useful building material, comes with an ecological cost. The production and use of concrete outputs considerable amounts of CO2 and typically causes extensive disruption to the local environment during installation.

Helical piles, conversely, are manufactured entirely from steel. Of course, the production of steel material also has a carbon impact. But where helical piles shine is the reduced amount of raw material they need in order to deliver sturdy support.

On average, a helical pile foundation will require substantially lower volumes of raw material. Their compact footprint and high-efficiency design means they can hold the same amount of weight as concrete, while slashing material usage by hundreds or even thousands of tons.

Oh, and if you ever need to remove the solar panels for site remediation, the helical piles can simply be reversed out of the ground and recycled (or even reused).

Extreme Durability & Long Lifespan

A 150+ year-old helical pile removed from a lighthouse. Photo credit and license.

From the pile shaft to the adapter on top, every component of a helical pile is manufactured from steel. This gives them superior strength, extreme durability, and a very long lifespan.
Just how long can a helical pile foundation last?
It depends, of course, on how corrosive the soil is at your site. However if we assume the soil is not particularly corrosive, you could easily expect to see 50 years of reliable service and well beyond.
In fact it's not unreasonable to imagine a helical pile foundation lasting over 100 years before experiencing enough corrosion to affect its' integrity.
We're not just saying that, either, as we have several examples of long-lived helical pile foundations.
The Spit Bank lighthouse built in 1853, the Carysfort Reef Light in 1852, and the Thomas Point Shoal Light in 1875, are all helical pile structures that remain standing to this day.
Helical piles can also be galvanized to increase protection, a great solution for difficult marine environments or corrosive soils.

Helical Piles Versus Ground Screws: Which Is Best?

One of the foundation options currently gaining popularity in our region are known as ground screws, and they can create some confusion when talking about helical piles.

The first thing you need to know is that helical piles are not ground screws. Even though they seem similar on the surface, there are critical differences in how they work.

Ground screws are, like their name suggests, a very large screw designed for use in the ground. Like helical piles, they're installed by rotating them into the ground with a hydraulic drive.

That's pretty much where the similarities end!

Helical piles derive most of their load capacity from the helix plate, which provides a large surface area for soil to exert pressure on once it's installed. A ground screw, on the other hand, uses threads to lock into the soil and relies on friction along the shaft to prevent movement.

In dense and well-consolidated soils, a ground screw can be a good foundation option for solar panels. However, there are some limitations to the technology.

Loose or wet soils, for example, can greatly reduce a ground screws' load capacity and pull-out resistance. In areas where firm soil layers are further underground, a ground screw may not be long enough to reach that competent material and achieve solid bearing. Finally, you may find that pull-out resistance is lower with ground screws compared to helical piles.

Again, we want to make it clear that we have no issues with ground screws in general. For smaller solar arrays built on reasonably dense soils they can be a great solution!
However, large-scale installations on questionable soils may run into problems if using ground screws. In these cases, a helical pile solution is well-worth a look.

Summary & Conclusion

If we had to sum-up this entire article in a mere 3 bullet points, here's what you should take away from everything written here...

There's few doubts that demand for solar energy, from grid-scale to residential systems, will continue to grow in Central New York. But with thousands of megawatts needed before we reach state and federal climate goals, it's clear the industry needs to adopt better ways of building.

After all, if we use tons of concrete and disrupt acres of soil to install solar panels - is it truly the most environmentally-friendly energy solution?

It's time for a transformation in the way we support solar energy, using a foundation that provides all the strength you need in a fraction of the time or ecological impact. Other regions of the United States have already enthusiastically adopted helical piles, and we can't afford to fall behind in New York.

Because if they can build a 3,300 acre solar farm in Canada on over 220,000 helical piles, there's no reason for us to ignore this impressive foundation technology any longer.

Whether you're currently planning a solar energy project or simply dreaming about one, get in touch with our team at CDP Excavating. We're here to make your entire foundation process impossibly easy, from initial designs to the final pile.

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