I may have lost you there.. I use the insurance term as proxy for the "additional life" that was only given when the DNO replaced some components that despite being rated for 100A, were more fitting as museum pieces! 

When I broadly mentioned circuits needing to be "shielded", it was not in the electrical sense, a better word may have been "cushioned". Specifically that when inverters and similar components are added to a household, some components that protect other circuits like RCDs type AC need replacing, ideally with RCBOs type A. We had a mid sized plastic consumer unit and that went a few months ago, as part of the prep.

The possibility of damage from surges doesn't increase with 'high powered' devices.

In fact the device most likely to be damaged by a surge or spike on the mains is a landline telephone or internet router, supplied by copper wires.
That's because there can be a voltage difference between the mains and the telecom cables.

We had our supply upgraded to 100A but only after a few years and another visit did I feel they had given us that insurance.

I was referring to 'insurance' as a metaphor.

The size of the service fuse doesn't change the susceptibility to damage from surges.

Price of components can also be driven by volume and other considerations like supply chain requirements to recoup r&d costs

Phoenix Contact surge arresters dominate the commercial market.
There are thousands of types in their catalogues.

They are proven to be affective because Pheonix Contact are based in the Black Forest, in the south of Germany.
That area has the highest number of lightning storms in Europe.
They can easily test products in real-world conditions as well as a laboratory.

It's relatively easy to make a surge arrester which protects equipment from a single spike.
The key point is what then happens to the arrester?
If it doesn't recover to full operational specification, then it's useless.
The next surge will get through.

Buyers are prepared to pay more for an anti-surge device that is more likely to provide protection.

Price of components can also be driven by volume and other considerations like supply chain requirements to recoup r&d costs. 

my understanding is that arcing detection is not required for new circuits unless it is a shared use property?

That's correct.

I was mentioning it as something which would be a future requirement.

Both arc-detection and surge suppression devices (SPD) are like paying an insurance package.
Even if you decide not to implement them, you should at least know that they are available options and why.

There are also different levels of protection offered, according to the specification of the devices you choose to install.

Your SPD might do all that you want at £20.

On the other hand, I use high-end Phoenix Contact suppression systems on both mains and PV panel connections.
The pair in the consumer unit which receives the mains incomer cost substantially more than £100.

There are reasons why some insurance premiums cost less than others.

As for SPD protection, for the extra £20 or so when getting a new unit, it was a no brainer. It also helped us removing the ad-hoc surge protectors we had like to stop the boiler PCB blowing up when power comes back following a black-out.  

Yes, they state that there's RCD protection inbuilt to the inverter.
But we don't know to what extent that offers protection to the inverter itself,
nor whether that protection covers appliances which are connected to the always-on port.

As matters stand, that integral RCD would still leave the supply cable and isolation switch unprotected.

I don't like having any conductors leaving the distribution board without both over-current and earth-leakage protection.

The regulations for new installations are even tighter.
You now need ARC-detection trips within the consumer unit.

Those will disconnect the circuit in the event of cable damage within the wall - perhaps vermin eating the insulation.
Whether that measure will reduce house-fires or not is too early to say, but insurers like it.

Just wanted to share this link that Solis posted on the sensitivity of the RCDs. To be honest, I will not be looking into it in much detail as just focus on my specific case is hard enough! 

But you may have a lot more to say and perhaps influence the powers. A bit more focus from them to advise each market (or perhaps Europe as a whole) may help reduce safety issues.. Or even ideally they will defend the safer standards should be used everywhere..

we are pressing Solis to reconfirm their recommendation to not use 30ma RCD.

I hadn't realised your reason for a 100mA trip was due to a Solis recommendation.

The 100mA and 300mA trip levels are made available for fire protection.
They're not intended to prevent damage to the human body.

It's a tricky issue because even a 30mA trip might not prevent the heart stopping, if, for example, the electrical path taken by the shock-current happened to be straight through the heart.

Designing an inverter so as to avoid all earth-leakage is difficult.
Solis might have struggled against a tide of consumer complaints that RCDs were tripping out,
and therefore started to recommend that 100mA devices were fitted.

We don't know the background story.

The goal is for it to be simple for family members   not need to change anything after the power comes back after an outage.  

That should be readily achievable as far as the inverter is concerned.

However, you might have other appliances in the home that 'trip out' if they're connected to the Solis port which doesn't stay live during an outage.
When the grid is re-energised there can be all sorts of spikes and surges which the suppressors in the inverter are unable to quench.

That's not Solis' fault.

And, if you should experience that occurring, then I might be able to help with advice regarding where the Surge Protection Devices (SPDs) are fitted within your consumer unit.
The distance between the SPDs and the circuits they protect does matter!
So ask here if you want further help with that.

None of this is commissioned at the moment. And there were plenty of drawings etc. The goal is for it to be simple for family members that absolutely do not want/need to know to switch it all on, as close to if it was a standard feed from the grid. And hopefully not need to change anything after the power comes back after an outage.  

I will post more, but right now we are pressing Solis to review and adjust the inverter settings and also reconfirm their recommendation to not use 30ma RCD. And confirm the "oversizing" as bi-directional RCDs and RCBOs are not available in all sizes.

Like FuseBox has a 50A 30mA RCBO TP+N (switched) 10kA (Type A) B Curve Bi-Directional that their odd 1.5x rule would exclude. 

So essentially trying to push them to prioritise the key questions they own and not seek distractions.