Solar Surviving Storms

The weak point in a solar panel mounting system is usually the number of roofing screws that hold the solar frame to the roof frame. This is especially important for tilt arrays, as they catch a lot more wind than a flush mounted system. For example, these images show a tilt frame (NOT SunLock) which was installed in a typical residential suburb in Queensland. It detached from the roof during a storm in November 2012, twisted and landed in a new location. 

According to the photos, failure occurred in at least two locations:

• the screws holding the front feet ripped out

• the upper halves of the telescoping rear legs ripped out from the lower halves

It is quite possible that if the storm had lasted a little longer, individual PV modules could have detached from the rails and flown through the air, damaging property or injuring people. This type of damage could have been avoided if the installer had been provided with the correct number of parts and a full installation manual, taking into account factors such as:

• Correct spacing between tilt legs (to provide enough roof fixings)

• Lower fixing capacity of Tek screws into thin steel battens (compared with screwing into timber)

• Lower load capacity of telescoping rear tilt legs (compared with a fixed length rear leg)

• Use of diagonal braces to prevent sideways movement

Note that when properly installed, a SunLock tilt frame will withstand once in 500 year winds. For full details refer to the SunLock installation manual or the technical bulletin on tilt legs.