question

I am not from Ireland so don't know the regulation but you could install shunt trip circuit breakers as your PV disconnect and one on your battery. Firefighters turn switch in meter box, causes the breakers to open.

It seems the guidelines are somewhat contradictory, the DC side of the PV array needs to automatically disconnect in event of the AC supply being disconnected

However backup power supplies are allowed, via a changeover switch. Not sure how they can work properly if they're supposed to automatically disconnect in a loss of mains

Here's the isolator switch section Through these requirements of Part B of the building regulations and I.S.10101, all domestic PV installations installed under this Scheme must:

• Provide an automatic (i.e., automatically operated by disconnection of the main AC supply to the building) shunt (or interlocked) isolation of the circuit (whether AC or DC, and two pole) from the solar PV modules into the building, as close to the solar PV modules as possible, and a maximum of 1.5m internally from the point of cable entry to the building. • Where the circuit from the solar PV modules does not enter the building, this point of automatic isolation must be within 1.5m of the solar PV modules. • For ground mounted system the shunt (automatic isolator) must be within 1.5m of the solar PV modules.

• This system of isolation shall automatically isolate the circuit from solar PV modules when the AC supply is disconnected to the building, i.e., a shunt or interlocked isolation function.

• ‘Shunt’ or ‘interlocked’ isolation of the DC circuit is the only acceptable manner of meeting the Building Regulation TGD B – Fire Safety (2017) for the purposes of this Scheme.

• For the avoidance of doubt the disconnection of the circuit from the solar PV modules must be automatic and operated by removal of AC supply to the building and must not be operated by means of a dedicated switch, pushbutton, ‘fireman’s switch’ or other manner.

• For the avoidance of doubt an isolation of the supply from the PV modules is required in ALL cases, whether micro-inverters, DC optimised inverters, where the inverter is within 1.5m of cable entry or any other configuration is used.

• This system of isolation must automatically reconnect upon restoration of AC supply to the building.

A warning label must be applied to the main external AC connection point to the building stating “In Emergency Solar PV DC Circuit Automatically Disconnected with Disconnection of AC Supply to Building” or an equivalent statement.

And here the section on backup power supplies:

Off-grid operation is defined here as a solar PV (and battery storage) system which is not connected to the electrical distribution system (typically a remote dwelling).

Backup operation is defined here as a solar PV (and battery storage) system which is required to provide electricity to the dwelling during periods of grid outage.

• Off-grid systems must comply with the requirements of this code of practice but do not need to meet the requirements of Section 4.8, and can achieve the requirements of Section 4.7 as per the backup operation requirements below

• Backup operation is permitted so long as the below conditions are met;

- The backup supply from the PV and battery energy storage system must be on the load side of the ESB meter and cannot feed any other premises.

- The requirements of I.S. 10101 must be met, particularly relating to the requirements of ‘standby supply’ and break-before-make changeover switch, and the requirements for neutral treatment in island mode and impacts on protection operation.

- There can be no circumstances where the PV and battery system will feed energy into the grid during backup operation.

- Ensure that, by design, loss of mains (LOM) protection is not compromised. This could be either by relocating LOM to ESBN-Customer interface or by interlocking LOM changeover switch.