Aah its complex. not all inverter systems are equal, transformerless systems effectively connect one side of the DC bus or battery  to one side of the mains and then flip which side 50 times a second. Clearly a fault to earth in such a system blows something, but if that is the supply ADS or the semiconductor switches that do the commutation is a guess !

Inverters with transformers have a floating DC side, although for EMC reasons one side often is earthed, or at least earthed to RF, if not connected directly.

There are quite a few good explanations on maker's websites.
Mike

Thanks, that makes sense, I'll have a look at the websites. 

Hi Jake. 

I agree with your assessment regarding the requirements for embedded cables in accordance with the COP. However, it is still advisable to avoid embedding DC cables whenever possible and to also minimise their length if possible. The guidance also says functional earthing of one of the current-carrying conductors is generally not recommended but may be necessary to comply with the module manufacturer’s requirements to mitigate the effects of Potential Induced Degradation (PID). MCS-approved inverters are typically equipped with integrated Arc Fault Circuit Interrupters (AFCI) for DC arc-fault protection and short circuit protection. These inverters continuously monitor floating systems for earth insulation resistance using insulation monitoring devices suitable for IT systems. Additionally, they provide surge protection, grid monitoring, anti-islanding protection, and temperature protection, thereby safeguarding the DC side of the system.

I have just completed a Solar /PV & EESS course this week and It is also worth noting that some insurance companies now mandate the inclusion of fire shutdown systems. This often necessitates the use of module-level power electronics, such as microinverters, which have the capability to shut down independently in the event of a fire.

- Andrew

PV Ultra SWA vs Normal SWA

The PV ultra has double insulation on the DC carrying cores which is then surround by a bedding then there is the SWA and the a outer sheath.  In my eye double insulation on the DC side of power generation in the home is a must. 

Other points worthy of note.  Individual micro inverters on the PV panels themselves.  These dependant. on brand and model allow for safe voltage/safer voltage per panel 1 watt when disconnected from the power invert intentionally or accidently or by damage.  Some also offer fast safe shut down in the event of a fire at the PV or the main power inverter.  This makes the system far safer for first responders. 

Interlinked smoke and/or heat detectors on all floors of the dwelling ENCLUDING the loft.

Some manufacturers offer training on their brand of inverter.  Have a look at SunSynk I am sure they have a Approved Installer program.

Once you have considered all the above, it is worth thinking about battery storage to make the most use out of the self generated power.  There are some good books out there like

Code of Practice for Electrical Energy Storage Systems

https://shop.theiet.org/code-of-practice-for-electrical-energy-storage-systems-3rd-edition

Then next part of the puzzle in Island mode / Prosumer / Earthing

Hi Sergio, what are your thoughts regarding: - “Then next part of the puzzle in Island mode / Prosumer / Earthing” A additional  earth rod is required, contactor for neutral-earth bond on systems uptown 8.8 kW inverters. Hybrid Inverters have an output for essential loads during Island mode.

not much of a puzzle - if there is any way it can operate as an island, i.e. without external mains, then it needs its own connection to terra-firma. This can be in parallel to, or instead of  any DNO supplied earth, which may in any case be lost when mains is lost if the network cables are cut.

And, when switching over from mains to inverter, when in the UK, due to ECSQR you need to make sure that at no time are two NE bonds in circuit. This does not apply in other countries, that do not have such legislation,  nor sometimes on a large site, where there are private transformers that mean there is local distribution as well as consumption. However, even when it is permitted some care needs to be taken if there are multiple NE connections, that large neutral currents are not diverted through earth paths of inadequate current capacity.

Mike.