Underconstruction shall be equalised so that there are no dangerous voltages between different parts

Wire-trays may not be used as the main connection for grounding: a cable shall be brought from the main grounding point to the roof and from there everything else shall be connected

NEN1010 does not specify a recommended value and just states that “the resistance shall be low.”

Scope 12 have set a max. value of 10 ohm. 10 ohm is still a quite high value and installers should be looking at values of 0.1 – 1 ohm.

• If a solar system is more than 50 cm away of any part of a lightning system, it has no impact on the design. Nowhere on the roof the DC-cables shall cross the outer-bound of the protection (it usually means the cables shall come thru a hole in the roof and not on the side of the building)
• If a solar system is less than 50 cm away, it must be connected to the lightning system. Wiring on roof shall be 16 mm2. Inverter ground shall not be connected to roof. In addition the DC-cables must be protected by a class I overvoltage device (usually an extra external box)
  • Installer must contact the installer of the lightning system if this will happen.
• In general cabling shall be done in such a way that + and – are kept together to avoid large voltage difference by induction (see below).

To avoid induction loops the runback cable should follow the path of the module connections.

(Image to come)