Bidirectional RCD socket or RCD FCU, are there any?

[JohnW2]

That is what I assumed to start with, but it seems I was taken in ...

Quite so - and, as I keep saying, the moment we find ourselves talking about products which (if they ever 'come') will not be coming with "a fitted BS1363 plug that can be plugged into any existing BS1363 socket" then I don't think we would any longer be talking about 'plug-in solar' in the sense that most people seem to be thinking about it.

Something which comes with a 'special' (not BS1363-compatible) plug which has to be plugged into a 'special' socket installed by an electrician, that surely is not 'plug-in solar' in any sensible sense ... and, furthermore, as for getting paid for export, that surely would rarely work with 'true plug-in solar', since there is no metering of export associated with the vast majority of BS1363 sockets into which it may be plugged (and not even necessarily plugged into the same installation every day ).

Looking at YouTube it seems the March announcement has started something similar here, with people jumping the gun, including some who we would have hoped had more sense, like efixx, who seem to be telling everyone there is no problem.

As I keep saying, I think we are wasting our time with this very premature and speculative discussion. In the meantime, there will undoubtedly be people who find ways of doing things which are not actually 'allowed' by laws and/or regulations, but that is true much more widely than in the context we're currently talking about. Let's face it, it takes only the click of a mouse button to buy (in the UK) things like ...

 

[ericmark]

since there is no metering of export associated with the vast majority of BS1363 sockets into which it may be plugged

The smart meter does measure export as well as import, however it registers them under two different MPAN numbers, so to be paid for export that number needs assigning to your meter, which is done remotely, so there is no reason why anyone with a smart meter is not paid for export.

With non-smart meters, there are it seems three types, one will run backwards so you get paid same for export as for import, the second simply ignores export, and the third has both import and export readings.

As to if at 800 watts you will export, well I would likely without a battery at 800 watts export half of what I would produce, this is the problem, without the battery, one will be importing on peaks and exporting in the troughts so with peaks being charged double what you get for the troughs unless you have first type of meter.

Which then asks the question, is a simple plug in solar any good? It will depend on the layout of the home, the battery pack feeding the freezer for example, a 400 watt panel will just about produce 70 watt over 24 hours in summer, so two freezers with 50% duty cycle is around 70 watt average, so a battery pack with two freezers could use the power from a 400 watt panel without any back feed into the grid. (Although it does grid tie, so it can supplement the output from the grid if solar is not enough)

What I am saying, is at 800 watt, there is really no need with a battery to have the ablity to back feed into the grid. I use around 12 kWh per day, and the 6 kW solar panels with a 5 kW inverter can produce around 32 kWh per day, on a SW facing roof. So with under 1 kW I would never need to export if I also have a battery.

But to distribute the power around the home, I would need to power parts of the house direct from the solar battery, for a owner occupier not too much of a problem, I could select some ring finals to connect to the battery, but for rental this would require extension leads to selected rooms, every home is diffrent, last house to access under the floor as run a new ring or radial final would not have been too much of a problem, with this house it would be a major problem.

So we return to

It shouldn't be DIY at the moment though? It needs installed by an electrician.

and yes with an electrician doing the work, we have many options, and in the main that is the best way to do it.

What we must remember is cost of solar on the roof is expensive due to needing scaffolding, fit solar where scaffolding is not required, and installation cost drops by a huge amount.

But, be it professional installed or DIY, we return to the same question, how to work out if the RCD is bidirectional or not. So if it means a new consumer unit to get the correct RCD then that bumps up the price, my last house had two RCDs feeding to old Wylex fuse boxes, where fuses swapped to MCBs, as RCDs fitted before we got RCDs built into the consumer unit, so there are other options other than fit a new consumer unit, and in the past we would fit a RCD double socket where we would plug in the lawn mower, i.e. a special socket for outside, and to fit a special socket for solar is not much different.

We had a requirement where a socket is likely to be used for outdoor equipment, so no RCD was required with high rise flats at the time, similar rules could be introduced for solar.

But the problem is the government announcement has short-circuited the natural progression, and promised balcony solar in months, it would likely be allowed in a few years anyway, and the industry would have caught up, just as type AC RCDs are no longer fitted, if in 2027 all RCBOs need to be bidirectional double pole switching, then plug in solar could be released for use where the CU is post 2027, or a certificate issued to say suitable.

I am sure many other ways could be found, including the EPS type of battery being permitted without upgrading CU, the problem is not really plug in solar, the problem is well publicised government announcements. We are now likely to see firms fitting solar fold, due to loss of business while waiting for the new plug and play solar.

What we want is each manufacturer to admit, these part numbers of RCD/RCBOs are not bidirectional. So at least we can look it up on a list.

 

[denso13]

ut the problem is the government announcement has short-circuited the natural progression,

April 2026 was stall a good month for installations, which was after the announcement. I can't find the figures for May yet.

Britain continues to break clean power records

Households across the UK continue to embrace solar power as the government accelerates its clean power mission.

www.gov.uk

 

[ericmark]

April 2026 was stall a good month for installations, which was after the announcement. I can't find the figures for May yet.

Good to hear, I do note:- in this street, there are two of us which over 10 panels, but most seem to only put up 4 or 5 panels, scaffold will cost the same 5 or 10 panels, so why so few?

 

[SUNRAY]

In fact, looking around here, my three up-front Type S RCCBs have(for convenience) been installed 'upside down'(supply at bottom) from how they would usually be installed in a CU but,

It wasn't that many years ago that RCCDs were commonly fed from the bottom in CU's.

 

[JohnW2]

It wasn't that many years ago that RCCDs were commonly fed from the bottom in CU's.

That's also true, of some, but all those I've dealt with have been fed from the top, not the least because (just like the 'Main Switch') the L if their 'output' was connected to a bus bar at the bottom.

 

[JohnW2]

The smart meter does measure export as well as import ...

So can my 'dumb' meter, but, even if I had access to them, the export figure would always be zero.

.... however it registers them under two different MPAN numbers, so to be paid for export that number needs assigning to your meter, which is done remotely, so there is no reason why anyone with a smart meter is not paid for export.

Merely having a meter which can measure export is not enough. As you say, one has to make arrangements for a supplier to look at that data and to pay for any export. To my mind, that destroys the concept of 'plug-in solar' - since if someone (if they could) just buys such kit and just 'plugs it in' to an existing socket (which I rather doubt will ever be 'allowed' in UK), few, if any, of them would be able to be paid for export (without 'formalising their PV installation').

When you started this discussion, you seemed to be putting quite a lot of weight on 'portability' - although, in reality, I think that 'portable' and 'paid for export' is almost an impossible combination. It seems to me that, rather than thinking of 'portable plug-in solar', people are really just thinking about it as a method of trying to circumvent some of the bureaucracy and regulations associated with 'installed PV' !

Yet again, I believe that all this speculative discussion is very premature.

 

[ericmark]

you seemed to be putting quite a lot of weight on 'portability'

Yes, I still think that is where plug and play shines over installed, for a tenant to be able to take the system with them to the next home, is the whole idea of plug and play.

It seems to me that, rather than thinking of 'portable plug-in solar', people are really just thinking about it as a method of trying to circumvent some of the bureaucracy and regulations associated with 'installed PV' !

Installed PV does have some advantages, over plug and play, but one thing I did not realise when we started was that in Germany to don't have plug and play as I had considered it.

trying to circumvent some of the bureaucracy and regulations

It seems the German system does not circumvent the bureaucracy and regulations, but was designed to get back some control. The plug and play came first, then the government regulated it.

To me plug and play should be just that, no paperwork, not extra little bits, simply plug it in. However, if we follow the German example we will need to fill in some paperwork, and we then start to look at the stages.
1) Simple plug in, and any excess is given away.
2) Add a battery and CT coil, so excess is stored for latter use.
3) Complete a G98, so excess paid for.
The last options will seem to have a problem, as once the tenant moves, he will take the system with him. And will need to complete another G98.
However, it seems with V2G EV points, the socket is registered, there is no reason why the same can't happen with solar.

Yet again, I believe that all this speculative discussion is very premature.

Yes, agreed, however we are seeing plug and play solar being used, before we get any change in the rules, as happened in Germany which was why their government changed their rules.

The UK government has caused the take-up of plug and play solar, due to the March announcement, there is now no going back, the moving finger writes, and having writ moves on: nor all thy Piety nor Wit Shall lure it back to cancel half a Line, Nor all thy Tears wash out a Word of it.

It has been like that for many years, Omar Khayyám born March 01, 1048 Died September 04, 1131. So this is nothing new.

 

[SUNRAY]

That's also true, of some, but all those I've dealt with have been fed from the top, not the least because (just like the 'Main Switch') the L if their 'output' was connected to a bus bar at the bottom.

If I had to make a statement about which way up the early MCB CUs were, I think my experience is of t'other way up, such as these

But I'd have to add that a lot depends on peoples experiences and what manufacturers they tended to favour.

Let us not forget that most 3ph boards have the busbars vertical in the middle and the protective devices are mounted 'top towards the middle' if that adds anything to the discussions.

 

[ericmark]

I used to like Merlin Gerin Electrical Consumer Units, became Schneider Electric.

The Seaman's board who box when you mixed MCB and RCBO they turned on opposite way to each other, one to the left the other to right. But the three-phase boxes the RCD was typically at the bottom, it in was always at the bottom with those boards, but seem to remember in the MCB/RCBO the terminals were at a different height, so no options which way around they were fitted.

I never even considered which way around they should have been fitted, seem to remember the early RCBO the RCD and MCB were separate units which bolted together. So it would take up 6 slots on the DB.