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Isolation of Solar PV

I came across a small (2 panels) Solar PV installation where the inverters on are the "micro-inverters", i.e. each panel has a integrated micro-inverter so effectively the panels deliver AC power into the property.

On this installation there was only a single AC isolator near the consumer unit. In the loft there was no isolator, just a junction box where the the cables come into the roof. I would have expected an isolator instead of the junction box, for maintenance and so the circuit could be tested & inspected upto the panels.

Does a single isolator in this situation comply with the regs and specifically 712.537.2.1.1? "To allow maintenance of the PV converter, means of isolating the PC converter form the DC side and the AC side shall be provided"

It seems it does but does not seem right.

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  • I'll leave others to comment on the regs side. If the regs can be seen as requiring an isolator, it seems silly in this case, probably because of a focus on central-inverter systems with many panels in a string. Two panels on a microinverter are probably not even series connected, but connected to separate inputs. Perhaps 40 V open circuit.  So it should be fine just to pull out the wires for 'maintenance'. (What maintenance that would be for a microinverter?)

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  • I'll leave others to comment on the regs side. If the regs can be seen as requiring an isolator, it seems silly in this case, probably because of a focus on central-inverter systems with many panels in a string. Two panels on a microinverter are probably not even series connected, but connected to separate inputs. Perhaps 40 V open circuit.  So it should be fine just to pull out the wires for 'maintenance'. (What maintenance that would be for a microinverter?)

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