There is a 2015 CE Code Rule in Canada that most Safety Authorities are already enforcing which requires roof mounted PV systems to have rapid shutdown.
Specifically CE Code 2015 Section 64-218
(1) A photovoltaic system rapid shutdown device shall be provided for a photovoltaic system installed on buildings or structures where the photovoltaic source or output circuit conductors installed on or in buildings are more than 1.5 m in length or more than 3 m from a photovoltaic array.
(2) A photovoltaic system rapid shutdown device shall limit photovoltaic source or output circuits to not more than 30 V and 240 V•A within 10 s of rapid shutdown initiation.
The rule is intended for fire fighter safety. When fire fighters arrive at a site, they may want to shut down power to the building in order to chop vent holes in the roof. The concern is that the PV wires may still be live even when the power to the grid is removed. The fire fighter cutting vent holes could be at risk of cutting through a live wire.
This will mean that every solar install needs some means of disconnecting power to within 3m of the PV array. HES has a number of different methods for accomplishing this and it will depend on the type of system or equipment you are using. Options include custom Rapid Shutdown combiners, ie. Fronius’s Rapid Shutdown Multi-Box, HES’s universal RSD rooftop combiner, or the MidNite Birdhouse connected to MNEPV Disconnects. Note that Enphase and SolarEdge inverters can be installed without need for a secondary Rapid Shutdown device.
Installers should be aware of this new rule and be prepared to add the appropriate equipment to comply with 2015 CEC rules.
This is a very controversial rule as some people believe it doesn't belong in the electrical code, but should be written and enforced by the local municipality governing the specific fire department. This would prevent issues such as installing additional failure points (Rapid Shutdown System) that are never used. For example, some fire fighters do not vent roofs, or in some areas there is no fire fighter coverage (off grid cabins).
Needless to say, it is in the code and installers must comply.