basically yes, Cable  is sized by thermal and VD considerations. The complication is that the PV generated current flows the wrong way, compared to a traditional load, so the voltage drop is reversed - unsurprisingly the voltage ends up being  higher at the generating end of things. All in verters that have approval must wind down if the terminal voltage gets too high.

The connection of PV to the grid requires DNO approval, and one reason for this so they can be sure that nothing will be connected that can push so much back into the DNO network that it causes a problem, either of over current, or over voltage.

Mike

(Obviously also check for ADS / adiabatic etc also as normal)

BS7671 does not specify anything special wrt. voltage drop (rise) but both for economic reasons and to avoid the inverter(s) disconnecting prematurely on the G98/G99 interface protection the custom is to work to a somewhat reduced limit, i.e. normally 1% AC for domestics, as per the IET Code of Practice.

Yes, generated electricity not used on site will flow "backwards" through the cutout.

Any connection in excess of 16A/ph will need prior consent from the DNO per EREC G99. This will include the DNO assessing the capacity of the network, protection etc, require any network upgrade works (including, if necessary, the "company fuse") to be completed at the customer's expense, and result in a site-specific Connection Agreement being signed. If the total generator (inverter AC) capacity exceeds the export limit in the connection agreement - assuming it's allowed by the DNO - there will also need to be an export limiting scheme in accordance with EREC G100. This will need to be noted in the grid application. Clearly this will need to be coordinated.with the company fuse, to avoid such things as causing it to blow following a sudden loss of load...

You might wish to read the ENA guide to the connection process: https://www.energynetworks.org/industry-hub/resource-library/g99-type-a-summary.pdf

(Obviously also check for ADS / adiabatic etc also as normal)

BS7671 does not specify anything special wrt. voltage drop (rise) but both for economic reasons and to avoid the inverter(s) disconnecting prematurely on the G98/G99 interface protection the custom is to work to a somewhat reduced limit, i.e. normally 1% AC for domestics, as per the IET Code of Practice.

Yes, generated electricity not used on site will flow "backwards" through the cutout.

Any connection in excess of 16A/ph will need prior consent from the DNO per EREC G99. This will include the DNO assessing the capacity of the network, protection etc, require any network upgrade works (including, if necessary, the "company fuse") to be completed at the customer's expense, and result in a site-specific Connection Agreement being signed. If the total generator (inverter AC) capacity exceeds the export limit in the connection agreement - assuming it's allowed by the DNO - there will also need to be an export limiting scheme in accordance with EREC G100. This will need to be noted in the grid application. Clearly this will need to be coordinated.with the company fuse, to avoid such things as causing it to blow following a sudden loss of load...

You might wish to read the ENA guide to the connection process: https://www.energynetworks.org/industry-hub/resource-library/g99-type-a-summary.pdf