One idea we thought of is making the house solar ready if in the end we do not install solar panels during the renovation process because of the sheer number of things that need to be addressed. The idea is that if the walls are open, this is the time to do something.
The size and material of the conduit is dependent on someone's intentions of installing PV or thermal panels in the future. If it is PV then 1" electrical conduit is fine. For thermal, it should be either 2 x 1.5" or a single 2.5" ABS pipe. For the thermal the run needs to be very close to straight to be able to feed in insulated flexible copper pipes.
Apparently, it is much easier to install the copper lines while the walls are open. With 50' coils of the flexible copper, it means that there are no soldered joints that could fail inside the walls, but they are much more difficult to feed through conduits.
We also were directed to the NRCan Solar Ready Specifications which include:
(1) 2-2" c-vac conduits from mechanical room to attic, to allow for future Thermal and Photo Voltaic installations.
(2) Pre installed plumbing connections to allow for less disruptive future solar hot water installation.
(3) Pre-wired electrical at the location of the future solar hot water tank .
(4) Roof and mechanical room layouts showing future solar panel and hot water tank locations provided to homeowner.
(5) Sticker labels on the mechanical room conduit and the hot water tank indicating the Solar Ready connections.