We are asked frequently, can I put solar pool heating panels on a flat roof? The answer is yes, if there is no suitable pitched roof, it can be done. But we don’t do it for very good reasons.
Ideally, solar panels are mounted on a pitched roof facing south. West and east roofs can also work. However, where shading is a concern, of if you don’t want solar panels on the from of your house, a flat roof is a viable alternative. Pitched roofs are unquestionably better. Facing the panels toward the sun lowers the angle of incidence and provides the most energy from the sun’s radiation. In the winter months this is particularly important because the sun is lower in the sky, and the winter is when you need solar pool heaters to perform as well as possible.
Flat roofs introduce some challenges, like system drainage and keeping panels free of debris. As you can see in this photo, heavy debris from pine trees causes buildup of vegetation that needs to be periodically cleared for best performance. Pitched roofs tend to shed debris through wind and rain action (although some debris can build up, particularly in separated tube type panels.
Flat roofs are definitely viable options for solar pool heating panels, but not recommended if a good alternative exists. We don’t do flat roofs because of specific issues with drainage and risky roof penetration options available on the market for solar pool heaters. Some dealers have been known to just glue down blocks and mount panels to those blocks… not a good idea. We highly recommend against flat roof installations of solar pool heating panels. More here.