One of the biggest concerns for homeowners thinking about installing solar is the effect it may have on their roof. Logic would say that putting 85-200 holes in your roof could be risky but let's look at the facts. Roof penetration to connect solar mounting hardware has come a long way in the last decade. In the early days, a bracket was secured to the roof over the shingles and a butyl tape or structural roof sealant was used. This provides a watertight seal on day-one but as the shingles erode around it, the risk of leaks may increase. Alternately, some manufacturers modified a product called a 'roof-hook' that was initially designed for clay tile roofs. This 'hook' fastened up under the shingles and had a flat steel bar that extended out in a partial U-shape to connect to the mounting rails. Things have improved a great deal and most installations now use an engineered roof flashing made from thin aluminum or treated steel. This provides a watertight guard for the necessary lag screws used to connect the mounting hardware to the trusses located under your shingles and plywood. I almost always have one with me for 'show and tell'. Flashing is a traditional roofing method and, from my experience and conversations with roofers, is actually far superior to the shingles themselves. These flashings will outlast any asphalt shingles on the market today. So, a correctly installed solar system should provide 20+ years of leak-free operation.
In a recent removal of solar equipment to allow for replacement of the roof shingles, I was able to get some great photos of how protected the roof is under the shingles. The solar had been installed for about 6 years and the exposed roof was in dire need of replacement. Wherever there were panels, shingles were in markedly better condition. So, if holes in the roof aren't a leak risk and your shingles actually last longer when protected with solar panels, you officially have two more reasons to go solar.
Solar and your roof - happily ever after!
Sean Hammond is a professional renewable energy consultant and project manager based in Ontario, Canada.