A flat solar roof system typically consists of a load-bearing structure (or roof deck), followed by a vapor barrier membrane, an insulation layer and finally a waterproofing membrane over which the solar system is mounted.
No matter the chosen type of solar installation, the total roof system must be considered during the design stage to achieve a durable rooftop photovoltaic system. If one layer fails, the whole system will fail. If the roof needs to be repaired, the PV installation would need to be removed and re-mounted again afterwards, generating substantial financial and environmental costs. Choosing the right components is therefore critical to avoid damage and ensure a high performance, robust and long-term solution.
Rooftop PV investments are typically based on a financial projection of minimum 20-25 years, so the service life of the roofing system must at least match this period to maximize returns. Besides fulfilling its insulating and waterproofing function, the roofing system needs to withstand the increased foot traffic that will take place during installation and maintenance, in addition to the permanent weight of the mounting racks and solar panels themselves.