Most residential solar panels are installed on rooftops, often an ideal location for maximum sunlight exposure. Rooftop systems also install faster and at a lower cost compared to a ground-based system.
The amount of electricity a rooftop system can produce depends on the size of the house and the condition of the roof. A typical home might have a system that can produce between 3 and 6 kilowatts. For the system to work well, the roof should face south and not have any shade from trees or other buildings. Some roofs are not suitable for solar panels because of their size, shape, orientation, or shading from trees or other nearby objects including roof pipes and chimneys.
The best orientation for a rooftop solar system is anywhere between southeast and southwest. If the roof faces directly south, it will get the most exposure. But, east or west facing roofs can also work in some cases. At our latitude, the ideal angle for a roof is between 25 to 40 degrees, depending on the orientation, but any roof that gets full sun exposure can be a good candidate.
The solar panels are attached to the roof using special hardware that is designed for the wind load, snow load, and type of roofing material. The weight of the solar panels is very low, so the roof does not need to be reinforced.
Rooftop solar panels are attached to the roof using special hardware and sealants that are designed to be waterproof and secure for the life of the roof. The hardware is either attached to the roof trusses/rafters or, in the case of metal standing seam roofs, clamped directly to the metal seam without the need for penetrations or sealant. On average, one to two attachments are needed per solar panel.
When installed correctly, the attachments will not leak or cause any damage to the roof. In fact, the attachment location may even become more waterproof than it was before. This means that the system is designed to last as long as the roof and will not cause any problems with leaks or structural damage.
Each type of roof has different characteristics and types of mounting hardware:
Asphalt flashing roof attachments use metal flashing that slides underneath the shingles to provide a secure, waterproof seal. This ensures that there will not be any leaks even if the shingles fail.
Asphalt seal attachments are designed to attach directly to the shingles and waterproofing membrane, using the roofing material itself to provide a permanent seal.
Metal attachments are tailored to the specific brand and type of metal roof, such as pole barns with exposed fasteners or standing-seam roofs with hidden fasteners.
Tile roof attachments replace individual tiles at each attachment point with metal flashing that is shaped like the tile. Lag screws are used to attach the mounting hardware to the rafter.
Flat roofs typically use ballasted solar mounts without penetrations, where the solar panels sit in trays held down by concrete blocks, but these systems typically require maintenance and are not very suitable for winter climates.