Posted by: @majordennisbloodnok

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Posted by: @jamespa

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My personal opinion, which others may not share, is that the burden of proof now lies principally with those who would oppose, not those who would permit.  Put another way, if its good enough for German regulators, its good enough for me unless there is a specific reason for the UK being different.  However this opinion is purely personal.

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My take is a slight variation to that.

I don't necessarily think we should implement unless we can prove there are significant risks; I think we should instead be making the decision to implement anyway and then working through any risks to decide how to resolve them; in essence, a process of "taking away reasons to fail". Once again, though, my own opinion and others may vary.

 

I wouldn't disagree - put another way - tell the industry its going to happen and challenge them to deal with it.  I would however also set a deadline for implementation to avoid filibustering by the industry and set severe constraints on what impositions they can put on the plug in solar manufacturers, in order to avoid them making it impossible/unnecessarily expensive in practice.

That said I think your approach and mine amount to something very similar.  Having decided to implement anyway (your suggestion with which I wouldn't disagree) it would be madness, when identifying and working through the risks, not to learn from others, in other words for those who oppose (or who have identified risks) NOT to be required to explain what specific differences between Germany and UK make the risks different in the UK than in Germany, and also how Germany has dealt with the common risks.

Either way, the message is, get on with it rather than finding reasons to stop it!

Posted by: @majordennisbloodnok

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I don't necessarily think we should implement unless we can prove there are significant risks; I think we should instead be making the decision to implement anyway and then working through any risks to decide how to resolve them; in essence, a process of "taking away reasons to fail". 

I believe you are supporting to be able to plug the IKEA kits to a normal socket?

Not for the laws and/or regulations that require these uniquely bidirectional rcbos to be kept and so restrict the useful electrons?

I am saying this since if there is anything different here that precludes the use of the plug in solar that Germany found safe (with a UK socket, of course),  it is probably better for all to align them.

Posted by: @batpred

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I believe you are supporting to be able to plug the IKEA kits to a normal socket?

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No.

I am supporting the production and sale of solar microgeneration kits that can be installed by home owners in a plug and play style. I am not supporting any particular installation method, and I would only support installation by means of a normal socket if it meets legitimate safety concerns. I don't know of any other ways plug and play installation could be achieved, but that's not relevant since there are lots of other things I don't know too.

@batpred @majordennisbloodnok

I think all three of us are broadly saying the same thing, albeit with slightly different emphases, namely:

Given that the German authorities have deemed it sufficiently safe for Germany, and given also that Germany is a country that takes both engineering and safety seriously, DiY (ie no professional help required) plug in solar should be allowed in UK.  The only exception to this conclusion would be if there is a legitimate safety concern which cannot reasonably be circumvented.

Furthermore it can be presumed that a safety concern which also occurs in Germany with the same or lesser risk is not legitimate (ie either the risk is sufficiently small of 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.  Given that physics and biology is the same in Germany as the UK, and mains voltage and frequency is also the same, that could only occur if there is a difference in wiring practice between the two countries that materially affects the risk.

The point of the reference to Germany is that it establishes a basis for the presumption that permission will be given ( @majordennisbloodnok wishes to take as a given, whereas I wish to take it as a rebuttable presumption - a small difference of position).  This is as opposed to the default ie a presumption of denial.  It also establishes a reference point against which those who seek to deny can reasonably be asked to justify their position.

Posted by: @jamespa

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Furthermore it can be presumed that a safety concern which also occurs in Germany with the same or lesser risk is not legitimate (ie either the risk is sufficiently small of 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.  Given that physics and biology is the same in Germany as the UK, and mains voltage and frequency is also the same, that could only occur if there is a difference in wiring practice between the two countries that materially affects the risk.

I completely agree. 

Anything safety related would normally not take very long to identify.

Just adding the relevant addition to IET regulations (BS 7671), that 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 update refers to the BEAMA 2023 note, that itself just mentions "There is 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 focuses on labelling. 

The physics and biology do not seem to have been a consideration, but as @transparent mentioned, electricians are just expected to follow these regulations to the letter.

Changes made to regulations can essentially create new markets. If this happens in isolation (i.e. other countries do not require it), this "small market" reduces choice to the UK installer and ultimately costs the UK consumer.  

Posted by: @jamespa

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Further to the above DIY plug in solar (German - Balkonkraftwerke) is offered by IKEA in Germany ...

EUR999 for 4*450W plus a 1.9kWh battery, less 15% discount if you are an IKEA family member

I saw kits already on sale in the UK. Not comparable, but 800W panels with an 800W waterproof microinverter and fixings, all for £400. Tempting. I wonder if the lack of the 6 pages of MCS production and savings estimates will deter much of the public. 

Posted by: @batpred

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Posted by: @jamespa

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Further to the above DIY plug in solar (German - Balkonkraftwerke) is offered by IKEA in Germany ...

EUR999 for 4*450W plus a 1.9kWh battery, less 15% discount if you are an IKEA family member

I saw kits already on sale in the UK. Not comparable, but 800W panels with an 800W waterproof microinverter and fixings, all for £400. Tempting. I wonder if the lack of the 6 pages of MCS production and savings estimates will deter much of the public. 

The big question, which brings us full circle back to the catalyst for the original technical discussion, is whether it is legal to actually use one of those kits. It's perfectly legal to purchase and own one, but is it legal to plug it in?

And I don't know the answer.

Posted by: @majordennisbloodnok

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Posted by: @batpred

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Posted by: @jamespa

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Further to the above DIY plug in solar (German - Balkonkraftwerke) is offered by IKEA in Germany ...

EUR999 for 4*450W plus a 1.9kWh battery, less 15% discount if you are an IKEA family member

I saw kits already on sale in the UK. Not comparable, but 800W panels with an 800W waterproof microinverter and fixings, all for £400. Tempting. I wonder if the lack of the 6 pages of MCS production and savings estimates will deter much of the public. 

The big question, which brings us full circle back to the catalyst for the original technical discussion, is whether it is legal to actually use one of those kits. It's perfectly legal to purchase and own one, but is it legal to plug it in?

And I don't know the answer. 

I really have no idea

@majordennisbloodnok

For my money no advice can be taken.. I do feel the status is as usual favouring professionals. But is the enthusiasm of the willing public for net0 being curbed?

Essentially, this just needed legislation. In Germany these systems need some simple registration, people just hang them from the windows. 

The German VDE (that regulates the electrotechnical domain, website vde.com) approved a product standard for plug in solar devices late 2025. It defines what manufacturers need to test, etc, like: 

• Testing of inverters in accordance with IEC 62109

Their press announcement mentions "eight years of intensive standardization work, two published draft standards, the associated objection consultations with more than 1,250 objections in total, and finally the arbitration procedure.". And they limited the inverter at 800W. So it seems no stone was left unturned. 

In the EU, they may have passed some law a few years ago. These things connect to the low voltage grid, perhaps the transnational networks are regulated at EU level. The power limit for the inverter for these self installed systems seems to be 3500W. 

Consumers in the UK have been missing out. 

And if we are to extrapolate from our reg approach, Germans, Dutch, Belgium regulators would be dealing with significant safety issues. 😉 

Even if I am really curious about what the VDEs standard says, it is behind a paywall. 

Posted by: @jamespa

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I am trying to avoid being awkward but am genuinely finding it very difficult to accept that regulatory bodies in the EU are somehow incompetent, whereas ours are somehow competent!  I do accept that these countries have different wiring practices, but nothing so far seems to relate to these.

News that the German VDE is widening the plug in solar option, arguably opening it to above 800VA installations:

An update to VDE-AR-N 4105:2026-03 introduces a simplified connection process for small generation systems with inverter output of up to 800 VA. Under the new rules, this process applies to PV systems above 2,000 Wp, systems with storage, or those seeking remuneration, allowing system operators to complete registration themselves using a dedicated form.

The revised framework removes formal limits on module capacity within this simplified process.

Is the change proposed in the UK for plug-in solar for the maximum possible to plug into a UK plug?

Posted by: @jamespa

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@batpred @majordennisbloodnok

 

I think all three of us are broadly saying the same thing, albeit with slightly different emphases, namely:

 

Given that the German authorities have deemed it sufficiently safe for Germany, and given also that Germany is a country that takes both engineering and safety seriously, DiY (ie no professional help required) plug in solar should be allowed in UK.  The only exception to this conclusion would be if there is a legitimate safety concern which cannot reasonably be circumvented.

Furthermore it can be presumed that a safety concern which also occurs in Germany with the same or lesser risk is not legitimate (ie either the risk is sufficiently small of 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.  Given that physics and biology is the same in Germany as the UK, and mains voltage and frequency is also the same, that could only occur if there is a difference in wiring practice between the two countries that materially affects the risk.

The point of the reference to Germany is that it establishes a basis for the presumption that permission will be given ( @majordennisbloodnok wishes to take as a given, whereas I wish to take it as a rebuttable presumption - a small difference of position).  This is as opposed to the default ie a presumption of denial.  It also establishes a reference point against which those who seek to deny can reasonably be asked to justify their position.

what little I know on the subject is (and all subject to my misremembering or misunderstanding originally) 

*the UK has larger mains plugs to include a fuse, which are there to protect the house wiring from a faulty appliance. Continental plugs are not fused and the wiring is designed for that.

*the UK uses ring main configuration of wiring around the house to allow larger currents to flow with smaller cross-section wires 

*continental household wiring tends to all be of type direct to each socket, thus using more copper

So perhaps there is a difference between how safe the plug in solar would be in different countries. Without a full knowledge of the wiring regs and options in both countries it is tricky to judge.

The snag in any country is that wiring gets modified over time and few owners/renters know what is behind their sockets.