This discussion started elsewhere but may fit better here..

Posted by: @jamespa

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... a safety concern which also occurs in Germany with the same or lesser risk is not legitimate (ie either the risk is sufficiently small or does not in fact exist).  A 'legitimate safety concern' would therefore need to be one which does not occur in Germany at all, or which does occur in Germany but with a materially lower level of risk. 

I am as puzzled as @jamespa about what could have led to a decision in the UK to effectively mandate these "bidirectional" RCDs while in Germany they do not expect them for the Ikea DIY PV kits. 

The relevant addition to IET regulations (BS 7671) reads as follows: 

CHAPTER 53 PROTECTION, ISOLATION, SWITCHING, CONTROL AND MONITORING
530.3.201 Selection and erection of equipment for protection shall take account of appropriate use of either a unidirectional protective device or a bidirectional protective device.
NOTE: Product standards as listed in Appendix 1 for some protective devices, including RCCBs, RCBOs, circuit-breakers and AFDDs, require these devices to be marked to indicate if they are unidirectional e.g. “in” and “out” or “line” and “load” or arrows.

The IET update refers to the BEAMA 2023 note, that mentions differing guidance from industry bodies on whether a microgenerator should or should not be installed to the load side of any RCCB that is shared with other circuits, it does not comment on the source. But electricians are expected to follow IET regulations to the letter. 

Anyway, the current stance could be seen as restricting the use of DIY kits in the UK market, with the RCD needing prior replacement by an electrician.

So that the Public could lead the way, someone needs to demystify this risk.

I also wonder if the risk could be made acceptable if (assuming that there is one RCBO dedicated to the socket circuit), after plugging the DIY kit, the RCBO switch is flicked on and off a few times, some of this with a pause of a few seconds. If the RCD is still shown to work when the test button is pressed (as this IET Wiring Regulation is not retrospective) it could be left in use. If the RCD stops working, an electrician needs to swap the RCBO with one suitable for multi generation? 

@batpred I cant see how this risk relates to something that is different in German wiring practice than in the UK, unless German wiring practice has always used bidirectional RCBOs for all circuits, so that there is no chance that any randomly chosen circuit is on a unidirectional RCBO.  I frankly doubt this is the case unless someone can assure me otherwise.

My suspicions are, sadly, growing. 

If we want to ensure that this is not the case we would need civil servants that understand this stuff enough to grill the industry.  That doesnt mean that they need to be experts, just that they need to have a level of understanding to spot likely BS/protectionism.  Our culture (for 53 years out of 80) of low regulation and outsourcing government skills to industry, for better or worse, prevents that from happening.  

Posted by: @jamespa

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If we want to ensure that this is not the case we would need civil servants that understand this stuff enough to grill the industry.  That doesnt mean that they need to be experts, just that they need to have a level of understanding to spot likely BS/protectionism.  Our culture (for 53 years out of 80) of low regulation and outsourcing government skills to industry, for better or worse, prevents that from happening.  

I agree, I doubt that Germany regulators would have insisted on special types of RCDs without a good reason (and there would not be any before the spread of multi generation over the last decade). 

On our system, I think the MPs would be expected to do the grilling, or trading standards if they still have teeth. H&S do not seem to have grilled much around the flammable external insulation. 

Perhaps as @transparent says, the change needs to be from direct action by the Public that wants to use these things.. 

Posted by: @batpred

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I agree, I doubt that Germany regulators would have insisted on special types of RCDs without a good reason (and there would not be any before the spread of multi generation over the last decade). 

Germany, and other EU countries have historically had a single RCD for every circuit, not one per circuit. These are typically type A or F/B RCDs (Not AC type) and have been mandated since 2007 in Germany. Having multiple RCDs (4 to 6 circuits per RCD) is a fairly recent thing. 

Posted by: @batpred

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am as puzzled as @jamespa about what could have led to a decision in the UK to effectively mandate these "bidirectional" RCDs [...]

...

Anyway, the current stance could be seen as restricting the use of DIY kits in the UK market, with the RCD needing prior replacement by an electrician.

Note to readers coming across this topic in future.

In UK it is common practice to use the term RCD when referring to a device which detects leakage to earth, but has no over-current protection.

This 'shorthand' isn't to be confused with a writer referring generically to residual current breakers (rcd), as @batpred is here.

An rcd can be either an RCD or an RCBO.
In the sentences which I have just quoted, the residual current breaker being referred to is an RCBO.

Posted by: @transparent

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An rcd can be either an RCD or an RCBO.

In the sentences which I have just quoted, the residual current breaker being referred to is an RCBO.

Yes, the common practice here seems to be for the term RCD to mean an RCCB while the term RCBO (that also includes current over protection) is used for an RCBO. 

The British manufacturers association defines RCDs more generically, as below. 

The term RCDs covers a range of products some of which are listed below: 

• RCCB (Residual Current Operated Circuit-Breaker without Integral Overcurrent Protection)

• RCBO (Residual Current Operated Circuit-Breaker with Integral Overcurrent Protection)

• SRCD (Socket-Outlet incorporating a Residual Current Device)

• FCURCD (Fused Connection Unit incorporating a Residual Current Device) PRCD (Portable Residual Current Device)

• CBR (Circuit-Breaker incorporating Residual Current Protection) IC-CPD (In-Cable Control and Protective Device for mode 2 charging of electric road vehicles)

• MRCD (Modular Residual Current Device)

The issue that lead to mandating bidirectional versions for these types of circuits occurs in multiple varieties of RCDs. 

That may be so @batpred 

But you've used the term RCD (in CAPS) in a different way to the rest of us in this topic,
and meaning different things within your own posts.

That's why I needed to post clarifications.

Posted by: @transparent

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That may be so @batpred 

But you've used the term RCD (in CAPS) in a different way to the rest of us in this topic,
and meaning different things within your own posts.

That's why I needed to post clarifications.

I acknowledge I have not been consistent in all previous posts! 

The reason I followed your post mentioning rcd and RCD with the definitions BEAMA (and probably the IET) are using is just so that future consumers reading this can easily see the full range of devices potentially impacted. As they may be more than the ones covered in the IET regulations that electricians follow to the letter. 

Is there a way of testing this (without calling out an electrician)?

I am certain my rcbo bi-directional.

Our batteries and inverter are both on the same RCBO.

We did have a trip a while ago and both the batteries and inverter switched off.

Firstly @bash please post a photo showing that RCBO.
We might be able to work out which model it is, and therefore deduce if it's bi-directional.

Secondly, when you press the Test button on the RCBO, does it actually open the contacts?

Posted by: @bash

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Is there a way of testing this (without calling out an electrician)?

You can press the test button.

I posted a bit more about it above.

In our case, we could use MCBs.. 

We may look at it again if we find a detailed analysis of an instance where this RCD issue occurred. 

@transparent 

I will press the test button again to confirm, but it did completely trip the inverter when I last checked.

This is the rcbo.

Wylex 40A 30mA Type A DP C Curve Bidirectional Mini RCBO

https://www.screwfix.com/p/wylex-40a-30ma-type-a-dp-c-curve-bidirectional-mini-rcbo/4298x