Domestic EESS, island mode and island mode isolator

Question

Hello,
I need some help please

I am trying to understand if an 'Island mode' isolator is required for this particular inverter design.

The Solar PV Hybrid inverter has an 'EPS' (emergency power supply) output that we would like to use.
The inverter has an internal N-PE Bond relay.
In connected mode this takes its power direct from the grid.
In island mode the Hybrid inverter will have disconnected from the grid as per G98/99, and then the EPS is supplied from PV and/or battery.

So if the inverter is designed to disconnect from the grid during grid loss/outside protection limits is either an Automatic or manual changeover switch required?

gkenyon · Answer

Downdraft said: then we can rely on the inverter to disconnect and isolate from the grid in island mode. 
 I would caution, that I have been made aware that some inverters do not disconnect from the grid using devices that BS 7671 would recognize as providing 'isolation'. See Regulation 826.1.1.1, last para, which states 'A switching device suitable for isolation according to Chapter 53 shall disconnect all live conductors from the public distribution network.' 
 It's also worth remembering the provision in Regulation 21 of ESQCR [Regulation 22 of ESQCR(NI)] which conains the requirement that 
 21. Where a person operates a source of energy as a switched alternative to a distributor&rsquo;s network, he shall ensure that that source of energy cannot operate in parallel with that network and where the source of energy is part of a low voltage consumer&rsquo;s installation, that installation shall comply with British Standard Requirements . (British Standard Requirements means BS 7671 in the ESQCR.)

gkenyon · Answer

Sergio Fernandez said: Maybe BS EN 62040 series, or BS EN 50171 need to be updated to specifically include or exclude 
 I'm not so sure. 
 The product standards have a defined scope. 
 BS EN 62040 series is for UPS - Uninterruptible power systems. 
 BS EN 50171 is for CPS - Central power systems for systems like emergency lighting 
 
 EPS - new term coined for the purposes of what, and defined where? The term in IEC 60364 series is 'island mode', so 'island mode power' might be better than 'EPS'. 
 Sergio Fernandez said: gkenyon said: solar/battery inverters are not to those standards 
 Maybe those standard also need to be updated? 
 Why ? The standard covers inverters ... it's rather specific. 
 If we are talking about 'system' standards, this is perhaps supposed to be covered in IEC 62933 series, which covers electrical energy storage systems [of the kind we are looking at] but this set of standards is way behind schedule, and it's not being developed quickly enough. 
 Hence, manufacturers have nowhere to go, other than IEC 60364-8-82, to pin functional and related safety requirements on. 
 Given that, manufacturers would be perhaps advised to take care they are addressing all of the essential requirements of the relevant legislation, in addition to what standards are published.

Domestic EESS, island mode and island mode isolator

Community Rules & Guidelines