Ballasted Solar Energy Systems for Flat Roofs

A more traditional approach to mounting a solar energy system on commercial structures with a flat, or mostly flat roof is to use the ballasted array method. The ballast is simply the addition of weight at strategic locations to use gravity to anchor the arrays and racking. Ballasted arrays have been in use for years, having been subjected to tens of thousand real world conditions.

Some of the more important features and characteristics of ballasted solar arrays on flat rooftop include the following:

  • Ballasted systems are pre-engineered but flexible. Ideal ballast locations are prescribed, but minor modifications to meet unique conditions across many different roof configurations are possible.
  • Ballast materials are inexpensive and easy to use. Concrete blocks, prefabricated to specified dimensions, are common.
  • The use of pure ballasts to anchor a solar energy system eliminates the need to penetrate existing roof membranes and reduces leak risks. They are designed to work well on top of many built-up roofing surfaces without having to drill through the roofing surface.
  • The added weight and different roof loading profile from a ballasted system are well known and readily analyzed and often quickly approved by roofing design experts.
  • Installation routines are generally simplified, saving the buyer money. Future roof maintenance may be simplified. A ballasted system may be easier to
    remove and replace for planned or unplanned roof maintenance.

Ballasted Array Mounting as a Preferred Method

Beyond the inherent advantages for pre-engineered ballasted mounting listed on this page, Southern Light Solar finds other reasons to recommend this method to many of our commercial customers.

In Massachusetts and Rhode Island, for decades many commercial facilities have been built with very low slope and nearly flat roofing. Using this non-penetrating design option rarely limits our ability to offer the most cost effective and quick to install design for the size and production capacity needed. Where roof structures differ, the ballasted array packages can be easily adapted.

For example, it is common to have to design around a variety or parapets to avoid unacceptable shading. There are many different combinations of rooftop HVAC units, vents, filter systems, and other equipment and objects than must be routinely accessed. We are able to provide a ballasted design that minimizes solar power production across this wide range of conditions.

Because of our usual attention to detail, a ballasted array mounted solar energy system is the best solution for many commercial flat roof customers. For example, we make sure that every concrete block meets the minimum specification for freeze/thaw expansion suitable for New England.