Rooftop Sliding Snow Mass Causes Damage

When we install snow management systems to protect us from avalanching snow and ice, we tend to forget that there is a mass of both atop our roofs. Snow guards are designed to restrict this mass from exiting the roof in large amounts. We’ll highlight a problem often encountered with solar snow management. And we want you to know we can help! Alpine SnowGuards is always improving snow guard performance. We have the first and only solar snow management system on the market. Please email our expert customer service team for assistance.

Be Aware of Snow Guard Performance Pitfalls

There are times when a snow guard system does not perform as anticipated:

  • improper installation
  • improper amount installed
  • unprotected roof surfaces above a protected roof surface (ie solar arrays)
  • product may be wrong choice for geographic region
  • roof pitch and roof condition can also contribute








Impacts to Snow Guard Performance

On a recent project in New Jersey, a church’s snow retention system was ripped out of their roof because of sliding snow. They contacted us at Alpine to see if we could diagnose the problem. It was apparent a solar array (an unprotected roof surface) was installed above a protected roof mounted snow guard system.








Snow accumulated on these panels over time and slid off all at once, crashing into the snow guards below and dislodging them from the roof. This is referred to as “dynamic-load”. Most roof mounted systems are not designed to accommodate dynamic loads. For this reason, Alpine SnowGuards recommends a three-part system.

What Causes Snow to Avalanche off Solar Arrays

As we mentioned in our Solar Snow Dog blog, solar arrays are considered a “slippery surface”. This means that when the snow accumulates on top of the panels and begins to melt, the water layer between the snow and the panel creates a frictionless surface. This allows the snow mass to slide off like an avalanche. The snow simply evacuates the panel, and the large mass comes crashing to the ground. This causes problems for anything beneath the array due to lack of controlled movement.

Snow avalanching off slippery surface of solar arrays











A Closer Look at the Volume of Snowfall

On top of the church is a large array of solar panels: 34 panels total, stretching four panels high from ridge, to near the eave edge. The original roof installer did take precautions and installed two rows of a three-pipe snow retention system, salvaged from the existing roof, below the array near the eave edge. The problem they are having is that they did not account for the snow mass to be on the move when it struck the guards.

For example, let’s assume that the solar panels are 39” x 65” (17.6 sq. ft.) each and they received the 50-year snow load of 25psf. This translates to 34 panels x 17.6 sq. ft. per panel x 25psf snow load = 14,964 pounds of snow on the array. When this mass of 14,964 pounds began to move, it is easy to imagine how that force could wreak havoc upon the guards below.

Some advocate for the installation of only roof mounted snow guards below solar arrays as pictured. Alpine SnowGuards recommends a three-part system instead for optimal snow guard performance.














Alpine SnowGuards recommends our three-part solar snow management system. A minimum of a two-foot landing zone between the array’s leading edge and first row of snow guards.

Note: since the time of this writing, Alpine has innovated new products into our solar snow management system including the Solar Snow Dog. The Snow Dog is a 6″ pad-style developed in response to customer demand for a more extended version.

Improved Snow Guard Performance

Alpine SnowGuards is always innovating. Our snow guards for solar panels are the first and only ones on the market. We design and manufacture snow guards for all roof types. All products are rigorously tested in-house to ensure top-notch workmanship that is compliant with, and meets or exceeds industry standards and best practices. Products are also beta tested in the field, which provides valuable feedback and additional industry insight. Lastly, products are sent to 3rd party testing facilities where several performance modes are implemented to guarantee overall success of the products design and technical development. Some of our testing protocols include allowable load limits, maximum pullout weights, shear, and rain testing to ensure every product does what we say it will do.

Think snow!


We keep snow in its place


F T Y L Houzz30 pinterest

Sign up to start using our online project calculator!

Subscribe and keep up on the latest industry and Alpine news, products, and upcoming events!

Alpine SnowGuards designs, engineers, and manufactures snow management systems from our facilities in Morrisville, VT. We work closely with leading roofing contractors, engineering firms, developers, and roofing manufacturers to ensure we deliver quality products that do what we say they’ll do.