Ed Throws Trade Bodies Into Chaos Over DIY Solar!

I am not sure why we need to back feed into a 13 amp socket? There are a load of grid tie inverter/battery units which can connect to solar panels, so any item plugged into the unit is using solar and battery backed, without any back feed into a 13 amp socket. And they can't give away solar power without payment. 

Clearly a battery feeding back into the grid without payment would be a bad move. And not much better with just solar.

My first thought was designed to allow tenants to have solar, owner occupiers already have the option. But to get paid for export, one needs a second MPAN number, so the solar would need to be less than the base load, and smart meter only show every half hour, so one has no idea of the base load, unless one already has solar.

A iboost+ can use any export over 100 watt, which is OK with a 6 kW array, but with 800 watt maximum it seems a bit pointless. Unless everyone is going to get a second MPAN number. 

The phrase "balcony solar" or "plug in solar" or "grid tie solar" can equally apply to a battery/inverter with outlet sockets on the battery, which puts nothing back into the grid, to a device which does feed back into the grid. I note already a British plumbing outlet is offering solar which feeds into the grid, but there is a 99 day waiting list, but as someone who already has solar, I know solar really needs a battery as well, and also if I got balcony solar which feeds into the grid, who will know if the energy is from the G98 registered solar, or the plug in solar? I already have the MPAN number, so this would be a cheap upgrade for me.

But today's news, says we have too much solar, so to buy more solar when the export rate has already dropped from 15p to 12p seems a bit of a chance. 

GW7MGW said:

But add solar and the result can cause a massive over load

May be, may be not.

Lets not forget that these things were not designed for ring finals.

I see it as being similar to PV feeding into a 100 A CU - the load in the busbar depends upon where the PV is connected.

So the ring is protected by a 32 A MCB through which 32 A could flow. An additional 3.5 A could bypass that, but I would hardly call a 9% overload "massive".

Only one balcony system is permitted in Germany, so nobody would plug in three of them.

How often do we have Iz within 3.5A (800W) of In (or 0.67 In for rings)? In Germany I guess they'd typically  have 2.5mm² on a 16A radial for their sockets - so even method B there'd be about 7A spare - so even two units would be OK.

Our rings (requiring 20A per leg) would be a bit tighter - method B would only have 3A spare - but then it's likely the currents would be shared - so 3.5A split 3A one way and 0.5A the other would still be OK. Method A wouldn't have a margin of course.

Compared to the risk of someone plugging in a couple of 3kW fan heaters on the same side of the house when the CH packs in, the dangers seem limited.

In practice ring finals are almost never subject to sustained overloads and adding a local plug-in PV system isn't going to increase demand (if anything it can reduce it locally), so if it wasn't going to be overloaded before, it won't be after. 

   - Andy.

Simon Barker said:

More seriously, the whole point of these systems is that they are plug and play. No need to call out an electrician to hardwire them.

I realise that would be a terrible prospect for many on this forum

But I wonder if that's where there's a difference between Britain and Germany, where the Wiring Regulations could provide some better solutions.

In Germany apartments are more common, so plugging a system into an existing socket on a balcony is more practical and I would expect much more common. But in Britain balconies are not that common, I expect your typical British 'balcony solar' system will actually be mounted onto a wall, or other structure, flat roof etc, with it plugged into either an outdoor socket if there's one already available, or possibly a cable through a hole in the wall, plugged in inside, or a new outdoor socket.

In Britain it would help if there was some approved arrangement for an outdoor connection point, connected to an existing socket circuit - it would benefit from the Wiring Regs having some provision for something like the Wieland RST socket/plug arrangements used in Germany. 

In Britain it would help if there was some approved arrangement for an outdoor connection point, connected to an existing socket circuit - it would benefit from the Wiring Regs having some provision for something like the Wieland RST socket/plug arrangements used in Germany. 

And there we need to modify or repeal the plug and socket regulations that leave folk obliged to use 13A sockets in places they are really not the best idea, like charging visiting EVs and welders and indeed almost anything that really uses the full 3kW  for more than a few mins.

A simple standard connector , either that one or perhaps blue and weatherproof, with a flap over the socket when not in use on its own 16/20 or 32A  radial circuit perhaps.. If only such a thing existed !

Regards Mike. 

mapj1 said:

it would benefit from the Wiring Regs having some provision for something like the Wieland RST socket/plug arrangements used in Germany.

Does BS 7671 prohibit that arrangement? (Provided, of course, a dedicated circuit is provided for connection of the generating set, Regulation 551.7.2.1 now, was 551.7.2.)

mapj1 said:

A simple standard connector , either that one or perhaps blue and weatherproof, with a flap over the socket when not in use on its own 16/20 or 32A  radial circuit perhaps.. If only such a thing existed !

I assume you are hinting at an IEC60309 plug/socket, but I'm not sure whether I agree because being general purpose, it potentially brings its own problems, like someone plugging a 16A load into their their balcony solar socket, using it to power their 16A EV charger, or other heavy duty load. Which might be ok if connected on a dedicated 16A radial, but would mean the IEC60309 socket would be unsuitable for use as an outdoor connector for a plug-in solar system connecting to an existing ring circuit - that takes you back to using a regular 13A plug/socket.

Plus, there's a difference in construction - the RST plug/socket appears to have rather better shrouding of the plug pins than an IEC60309 plug and is more compact, fitting within the space of existing wiring accessories, so could be mounted on back-boxes and regular sized  accessories, whereas IEC60309 are normally quite a bit bigger with larger enclosures.

I can see some logic / benefit for having a clearly distinct and separate type of connector for generating devices.

I don't see the issue as being whether BS7671 prohibits the use of Wieland RST sockets, rather the issue is that as plug-in solar and plug-in battery storage is introduced into Britain, it would be beneficial for BS7671 define what the standardised plug/socket interface should be for those systems, where a dedicated socket is being provided.

If plug-in generating devices are now a consumer product, then BS7671 has to keep up with the demands being placed on wiring installations and propose suitable and safe arrangements for how these should be connected into the fixed wiring. It's happening in other countries, like Germany and their VDE standards, granted they are some years ahead of Britain and our BS7671 but we should be aiming to keep up !

TurboGen said:

I assume you are hinting at an IEC60309 plug/socket,

Can't be used to connect a generator to an installation without a "changeover switch", and even there, the thing on the wall would be a "plug" ... certainly no good for parallel operation because of possible 'live pins'.

The difference is the RST and similar (say, BS EN 61936-2 Type 2 plug and socket-outlet) is that the "live pins" are shielded.

In fact, a BS EN 61936-2 Type 2 connector would be a great idea, it's a British Standard, already ...

mapj1 said:

A simple standard connector , either that one or perhaps blue and weatherproof, with a flap over the socket when not in use on its own 16/20 or 32A  radial circuit perhaps.. If only such a thing existed !

And if you don't already have one fitted, your local camping supplies company will sell you an adapter lead with a 13A plug on the end!

No the Weiland would  fine by '7671, on its own suitably fused or breakered final circuit, and is actually exactly the sort of thing I'd far prefer to see on every new house; 'plug in solar ready' but our plug and socket regs make it really awkward to sell something to plug into anything that is not a 13A socket for use at home.

My point was that the plug and socket regs do nothing but cause trouble  for this sort of application and for a few other things, of which the biggest is caravans and outdoor power generally.

Now we no longer really have a mish-mash of 3 5 and 15A round pin plugs in common use,I reckon the 13A only rules could be safely de-fanged or even just repealed - and already for owners of caravans and workshops they are already widely ignored.

I'm less sure about BS EN IEC 61936-2:2023 Power installations exceeding 1 kV AC and 1,5 kV DC, as I'm not sure I've ever seen the connector that relates, or perhaps there is a numerical typo ?

Mike

No the Weiland would  fine by '7671, on its own suitably fused or breakered final circuit, and is actually exactly the sort of thing I'd far prefer to see on every new house; 'plug in solar ready' but our plug and socket regs make it really awkward to sell something to plug into anything that is not a 13A socket for use at home.

My point was that the plug and socket regs do nothing but cause trouble  for this sort of application and for a few other things, of which the biggest is caravans and outdoor power generally.

Now we no longer really have a mish-mash of 3 5 and 15A round pin plugs in common use,I reckon the 13A only rules could be safely de-fanged or even just repealed - and already for owners of caravans and workshops they are already widely ignored.

I'm less sure about BS EN IEC 61936-2:2023 Power installations exceeding 1 kV AC and 1,5 kV DC, as I'm not sure I've ever seen the connector that relates, or perhaps there is a numerical typo ?

Mike

Is a conventional 13A (or other) plug on this kind of thing really a problem that needs solving? These grid-tied inverters presumably do what they say on the box and won't keep pumping out juice once disconnected from the grid - in which case the live pins issue is a non-issue (at least no more than it would be with some conventional appliances which might leave the supply connected to capacitors or receive back EMF from a spinning down motor). In many respects these things aren't at all like conventional generators - it's only our insistence on using the word "generator" to describe them that's causing the problem. Call them, say, a negative load appliance, and things might fall into place more easily

   - Andy.