Viridian Solar - Roof Integrated solar PV

Maintenance

Solar panels should last thirty years or more. In this time it is highly likely that the roof covering will need either maintenance or replacement. An on-roof system will have tiles or slates behind the panels, so the solar system would need to be decommissioned and removed before a single tile can be replaced. A simple job that can be carried out from a roof ladder by a roofing contractor has become a significant task that requires scaffolding and the involvement of an electrician or solar installer. With roof integrated solar, there are no tiles behind the panels, so all roofing repairs can be carried out while leaving the solar system in place.

Installation

New regulations require all roof tiles to be fixed with nails or clips, making above-roof solar systems difficult to install since tiles may need breaking to reach the structure beneath and replacements often require adhesive bonding. By contrast, roof-integrated solar panels are straightforward in new builds, as panels and flashings can be fitted before the roof covering is laid. While often seen as more complex for existing roofs, integrated systems can actually save time compared to weatherproofing around numerous fixing hooks, and removing a small patch of tiles not only takes little longer but also provides spare matching tiles for future repairs.

Bird Infestation

Solar panels fixed above the roof offer a safe, sheltered area behind for birds to roost or nest. While this may at first sound like a good thing to do, householders with solar installations that have been colonised in this way have reported a number of drawbacks including noise and fouling of the panels, walls and paths below the nests. A small industry has sprung up to bird-proof above roof solar installations with spikes and mesh around the outside, further reducing their aesthetic appeal.

Clearly nests below the panels will reduce the free passage of cooling air behind solar PV panels increasing operating temperature and reducing energy yield (see next point).

Overheating

A reason that is commonly given for opting for above-roof solar PV ahead of roof-integrated solar PV is that above-roof systems will operate at a lower temperature due to better ventilation (although see section above). Since solar PV power output falls as panel temperature rises the argument goes that roof integrated solar will have a lower energy yield. Viridian Solar and researchers from Cambridge Univeristy have examined this effect.The published research found that the reduction in energy yield was very small, of order only 3%.