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PV flush downleads

lyledunn

New 3-storey house. PV panels on roof and inverter in garage on ground floor. Not unreasonably the client wants the downleads flush mounted. The proposal was to flush mount them in the masonry walls in steel conduit for the route from the loft area, down through bedroom on the top floor and TV room on first floor to garage on ground. No through boxes or the like to indicate cabling below. This is not a one-off situation as the client has a site of 40+ units. Done carefully, I can’t see too much of an issue but I just feel a tad uncomfortable. Any views?

Parents
  • 0

    Thanks Mike. What would be the merit in earthing the conduit?

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  • 0

    Thanks Mike. What would be the merit in earthing the conduit?

Children
  • 0 in reply to lyledunn

    Any voltage arising that might otherwise give an earthed person a shock when they drill into the cable - let's assume sun is shining, is mitigated by that current flowing mainly in the earthed conduit instead. The hapless driller is then holding a drill at or near earth potential rather than at DC voltage unknown.

    Who knows it may even fire some kind of ADS, but probably not very fast as the solar strings are current limited by nature.

    Without knowing the PV panel size, some knock out a few hundred volts as a series string and deserve commensurate respect.
    (For example the "sunny boy" series of  inverters expect 100-600V input to allow use of strings of 5-10 panels of varying sizes. 1 panel may be 30-60V  depending on the design.)

    Do not forget you will need to earth the solar panel frames - or at least most makers now recommend that.

    Mike

  • 0 in reply to lyledunn

    I would have expected the DC output of the panels to be isolated from ground, in which case accidentally drilling into one wouldn't be immediately dangerous.

    You may find that the inverter would spot a short to ground as part of its power-up self-test, though.

    It's common for the frame holding the panels to be earthed.  Do you know if it's being done here, and if so has anyone thought where that earth wire is coming from?

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