If solar panels are not installed correctly, they can damage a building’s rooftop. Unfortunately, poorly executed solar installations have soured some facilities managers and building owners on rooftop solar panels.
That’s a shame, because solar-wary building managers are missing out on the benefits of onsite solar power: Not just money savings and branding as an eco-friendly business, but also protection from the elements that solar panels can provide to a roof.
Not every roof is suitable to host solar panels. Roofs that are shaded by trees or nearby buildings may not get enough sunlight to make installing solar generating equipment worthwhile. And even sunny roofs won’t work for solar panels if the roofing surface is ballasted with gravel, if the roof is damaged or too old, or if the roof is not able to hold additional weight.
Of course you don’t want solar panels to fall through your roof! Nor do you want to have to remove solar equipment after its been installed to repair or replace a roof since that will wind up making things very expensive. Fortunately, many roofs can be easily upgraded to deal with these issues and successfully host solar panels. And many other commercial rooftops are already perfect for solar.
The good news is that up to 70% of the commercial buildings in the United States may be suitable for solar energy systems, according to a study done last year. For a roof that passes the solar test — gets plenty of light, is in good repair and is likely to remain that way for the 25-30 years of the average solar service agreement and can bear the weight of solar equipment — there are three common ways to install solar panels on a roof, according to Solar Power World.
1. Sloped Roof Mounting Systems
Used primarily on homes that tend to have pitched roofs, racking for solar panels is usually attached to the roof with bolts and other hardware. Bolts are sealed with material to stop water leakage, but anytime you put a hole in a roof, you increase your risk of leaks no matter how well you seal things up.
And if holes are drilled and bolts are installed incorrectly, they can damage roof shingles or other material on the outside of a roof. To avoid these problems, manufacturers have started making ballasted systems that don’t require penetrations even on sloped roofs.
Ballasted systems for sloped roofs essentially hang down from a hook at the top of the roof, distributing the weight of the solar equipment on both sides of the roof. Such systems may still require attachment to the roof through penetrations, but can reduce the number of holes and bolts required to keep everything in place.
2. Flat Roof Mounting Systems
Fortunately, most commercial buildings feature a flat roof or else a roof so sloped so gently as to allow the use of mounting systems kept in place by ballasting alone with little or no need for any bolts or other attachments. Reducing or eliminating holes in a roof cuts down or cuts out the risk of water leakage or damage to roofing materials from drilling holes and attaching hardware.
On flat or gently tilted roofs, racks of solar panels can be held down entirely with the weight of bricks placed into trays installed on the racking every few feet. This ingenious system of ballasting hits just the right balance, providing enough weight to keep solar panels in place during high winds but not too much weight for the average rooftop to handle. And polymers and other advanced materials have helped make solar racking that’s even lighter than traditional aluminum and stainless steel.
3. Solar Shingles and Building-Integrated Photovoltaics
Speaking of advanced materials, some of the most exciting developments in solar power involve recent innovations to combine solar technology with building materials known as BIPV. The most famous example is solar shingles from Tesla but other applications, such as thin-film coverings for building windows, allow components of a building to act as their own photovoltaic power generators, eliminating the need for traditional solar panels.
We’ve been keeping a close eye on this technology and we’re eager for it to mature. So far, the use of BIPV has been relatively limited, so its performance in a variety of climates and locations remains to be proven. Also, since the technology is new, it lacks a track record. How well will BIPV age? Will it still produce solar power at levels comparable to traditional photovoltaic solar panels after ten or twenty or thirty years?
These questions can only be answered by future experience. But early indications are that BIPV applications produce power less efficiently and more expensively than traditional panels. BIPV may be more practical for new construction than for retrofitting existing buildings. And it may be worth the extra money if a building’s designers want to hide the use of solar power with materials that blend in to the building’s covering.
Other Benefits of Solar Panels
Once installed, solar panels can provide surprising benefits to a roof surface, to the building space beneath the roof and to the people who use the building.
For example, studies have indicated that solar panels don’t attract heat, as some people think, but instead, can provide enough shade to cool a roof down by several degrees on a sunny day. A cooler roof can lead to a cooler interior, helping save money on air conditioning.
Solar panels can also help protect a roof’s surface material from damage by sunlight, rain, and hail.
Finally, for schools and colleges, a solar energy system right on campus can serve as an educational tool for workforce development as well as a variety of STEM disciplines and even business and finance.
Go Solar, Get a New Roof
A valuable side-benefit of going solar using modern solar financing is that a building may qualify to get a new or restored roof with no upfront cost as part of a power purchase agreement or solar service agreement.
One of the biggest challenges for schools, hospitals and other businesses and organizations that want to go solar on site is that their roof is not solar ready. It may need repairs before it can hold solar arrays. Or the roof may even be scheduled for replacement in the next few years, requiring the solar panels, racking and other equipment to be moved, adding significant cost to a solar project.
As a solar developer with many customers from K-12 institutions and universities, we know just how daunting it can be to think about replacing damaged or outdated roofs as a regular part of building maintenance. When you add solar panels into the mix, the need for good roofs increases.
With our Resilient Solar + Roof Restoration® package, on qualified roofs requiring repairs or facing replacement Secure Futures applies a high-quality roof coating that can extend the life of a roof for decades. We work with qualified roofing contractors to extend the warranty of a restored roof for 25 years. Since we merge all costs for roof restoration into the service fee structure of a solar project agreement, building owners can enjoy the benefits of a restored roof under warranty protection without the capital costs of a full roof replacement.