Earthing the conduit wouldn't provide ADS - so you can't rely on that for shock protection from penetration by nails etc - so the steel would have to provide protection by purely mechanical means (and the wiring inside to meet double/reinforced insulation requirements - e.g. insulated & sheathed, not just ordinary singles) (presuming it's not SELV/PELV.) Whether steel conduit provides sufficient mechanical protection from the likes of paslode type nail guns, is perhaps the question.

   - Andy.

Earthing the conduit wouldn't provide ADS - so you can't rely on that for shock protection from penetration by nails etc - so the steel would have to provide protection by purely mechanical means (and the wiring inside to meet double/reinforced insulation requirements - e.g. insulated & sheathed, not just ordinary singles) (presuming it's not SELV/PELV.) Whether steel conduit provides sufficient mechanical protection from the likes of paslode type nail guns, is perhaps the question.

   - Andy.

it does not need to provide rapid ADS, it just needs to ensure the drill bit is earthed, and provide a bonding like return to earth path - same thinking as the old bathroom bonding without the fast acting RCD.

On transformer-less inverters the strings alternate between being one way across the mains and then the other at 50Hz, with some wave shaping electronics and/ or with symmetric filtering - like this.  Note that  as the H bridge transistors switch  alternately, the mains live is routed to one side of the PV array or the other so the DC polarity is always correct.

Simplified transformer-less inverter control electronics not shown - the side of the AC shown as  'earthy' is the neutral.

The ones with  a high frequency transformer, rectifier and then 50Hz commutation may fully float the PV strings relative to earth or may earth one side of the DC  for EMC reasons.

HF transformer kind - to left the DC from the panel is made into a supersonic square wave and transformed up or down and then rectified. The rest of the design is as per the transformer-less one above.

Mike.

Coming back to the Sunny Boy ones, on at least one common model they do say to earth negative side of the string, which makes the positive side an immediate shock risk during the day.