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Where can a PV array be connected?

Chris Pearson

I suspect that a PV array would normally be connected between the meter and the first DB, but can it be connected more peripherally please?

The most suitable area of roof is at the opposite end of the premises from the electrical origin. However, there is a small DB with spare ways adjacent to the loft space. It supplies one lighting and one socket circuit and is seldom significantly loaded. The distribution circuit from the main DB is 16 mm² singles (with the live conductors being sheathed). As far as I can see, it travels through under-floor voids and is boxed in with other services as it ascends in a bathroom so RCD protection is not required. If the inverter can be situated in the loft space then only a short length of AC cable would be required.

This is what I have in mind.

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    But that will be longer than the breaking time alone so ADS times need a re-visit.

    Usually not an issue - once the DP RCD has tripped, the PV becomes a separated system - the inverter may still be putting 240V L-N but as nothing is referenced to Earth, the shock risk (to Earth) is eliminated.

    For MCBs the disconnection time is less onerous as the circuit to the inverter is by definition not  a final circuit (it doesn't directly supply current consuming equipment) so despite it's low rating (e.g. 16A) only needs to meet the 5s disconnection time requirement (for TN).

       - Andy.

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  • 0

    But that will be longer than the breaking time alone so ADS times need a re-visit.

    Usually not an issue - once the DP RCD has tripped, the PV becomes a separated system - the inverter may still be putting 240V L-N but as nothing is referenced to Earth, the shock risk (to Earth) is eliminated.

    For MCBs the disconnection time is less onerous as the circuit to the inverter is by definition not  a final circuit (it doesn't directly supply current consuming equipment) so despite it's low rating (e.g. 16A) only needs to meet the 5s disconnection time requirement (for TN).

       - Andy.

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