Plug in solar

[ebee]

I will not muddy the waters by suggesting that a bog standard house is one circuit (from the cut out) - remove that fuse and you have lost that one circuit.

Ignoring the fact that you might add wind, rain or sun (or a squirrel running in a cage wheel) as an alternative or an extra supply.

 

[JohnW2]

I will not muddy the waters by suggesting that a bog standard house is one circuit (from the cut out) - remove that fuse and you have lost that one circuit.

Quite so. I wouldn't call that "muddying the waters" since it's really just explaining, by example (I've used different examples), why the BS 7671 definition of "a circuit" is not really fit for purpose

Kind Regards, Johnel running in a cage wheel) as an alternative or an extra supply

 

[denso13]

Given two OPDs [say an MCB in the CU followed by an FCU (with fuse) somewhere along the length of the 'physical' circuit run (i.e.'all the wiring') ], the upstream device (MCB in CU) will, indeed (per BS7671) define the entirety of that 'physical circuit' (including any branches or unfused 'spurs'). However, the other OPD (fuse in FCU) will define everything downstream of the OPD as being the entirety of one circuit, thereby leaving eveything upstream of the FCU as being a separate, second, 'circuit'!!
So, depending upon how one looks at it, such a situation can satisfy the BS7671 definition of one circuit OR of two circuits

I do get all that but I still think, for a DIY install, then it would be everything that the CU MCB turns off.

 

[denso13]

will not muddy the waters by suggesting that a bog standard house is one circuit (from the cut out) - remove that fuse and you have lost that one circuit.

Or remove the substation fuse and a whole area goes down. Does that mean one circuit covers multiple houses?

 

[ericmark]

The arguments simply show how plug in solar can't fit every situation. All the trade bodies recognised this, but as they found out first in Germany, and then here, if you don't legalise it, people will use it anyway. So better to legalise and lay down some rules, than to let it be used with no or little control over what is fitted, it was a case of risk assessment.

If I wanted to fit plug in solar, I would first install a socket near to where the solar is to go, and likely piggyback on a 16 amp RCBO already supplying an outside socket, which does not have essential equipment like a freezer already connected to it, so really it would not need to be plug in to start with.

 

[denso13]

The arguments simply show how plug in solar can't fit every situation.

Of course, no one has ever said it did.

 

[JohnW2]

Or remove the substation fuse and a whole area goes down. Does that mean one circuit covers multiple houses?

Seemingly, yes, per BS 7671 definition of ' a circuit' - which I why I've said that I don't think that definition is really 'fit for purpose'!

it works, or nearly works, in the simplest of situations, but once things start getting more complicated, it only works if qualified by a fair degree of common sense - so it can hardly be regarded as a sensible 'official definition', can it?

 

[denso13]

so it can hardly be regarded as a sensible 'official definition', can it?

Perhaps, but I'd expect any approved instructions to give guidance which should be understandable by a DIY'er.

 

[JohnW2]

Perhaps, but I'd expect any approved instructions to give guidance which should be understandable by a DIY'er.

Hmmmm. I don't think it would be wise for you to hold your breath whilst waiting to see such instructions.


If BS 7671 does not provide an unambiguous and reasonably 'comprehensive' definition, then I'm not sure that we can be confident that "approved instructions" would, can we?

 

[UKMICKY]

So in theory if I wanted to take this to the extremes which some people out there would do . Providing If it does end up one 800
Watt system per circuit.

I could run 2 x 800 watts systems from the garage on the 2 seperate circuits and
another 2 x 800 watt systems from the ground floor and first floor rings in the house

So that 3200 watts through plug in solar.

I’m sure when they thought this up there was no intention to permit a diy option providing that much generation.

 

[UKMICKY]

It's a quantum circuit!! What happens when you observe it?

Well observation changes its state .

So , If it’s on ,then when the inspector comes to check on things , when he observes it ,it would change its state to off .

Quantum insurance against prosecution

 

[denso13]

that 3200 watts through plug in solar.

The maximum sum of wattage permissible is 2000, so two 800w units. It's still currently only one per household though, under different regulations.

 

[denso13]

Hmmmm. I don't think it would be wise for you to hold your breath whilst waiting to see such instructions.


If BS 7671 does not provide an unambiguous and reasonably 'comprehensive' definition, then I'm not sure that we can be confident that "approved instructions" would, can we?

I'm still not sure how "everything that a breaker turns off from the CU is one circuit" doesn't work in the vast majority of cases. If there is any doubt they'll be directed to seek professional advise.

 

[pcaouolte]

So in theory if I wanted to take this to the extremes which some people out there would do . Providing If it does end up one 800
Watt system per circuit.

My 4 way extension lead says max 3000 watts. It must be ok for 3 x 800 watt panels, maybe it would cope with 4 when it not too sunny?

 

[ericmark]

My 4 way extension lead says max 3000 watts. It must be ok for 3 x 800 watt panels, maybe it would cope with 4 when it not too sunny?

I know said tongue in cheek, but this is the problem. If more than one per household, how do you stop people doing something daft?

Looking at my power use, max this month 20.3 kWh and Min 10.8 kWh and at that clearly my system is well below capacity, and it is highly unlikely plug in solar will cause any problems except for four sockets clearly marked EPS.

But, like many house designs, the living room is on the sunny side of the house, the ring final circuits are split North side and South side, so in warm weather the South side would likely have both plug in solar and an AC plugged into the ring final.

So with the limit 2000 watt panels and 800 watt inverter that means in essence 800 watts going from the inverter to the portable AC unit without going into the consumer unit.

So we look at

The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.5 refers). This can generally be achieved by:
(i) locating socket-outlets to provide reasonable sharing of the load around the ring
(ii) not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile from the ring circuit
(iii) connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit
(iv) taking account of the total floor area being served. (Historically, limit of 100 m² has been adopted.)

So if the inverter and AC are around the centre of the ring, unlikely to be a problem, but if biased to one end, overload could happen.

So the question is, can a non electrician, be instructed about the dangers, in any instruction set issued with the kit? As an electrician I had to do a test to show I could read a book, I had the book before the exam and during the exam, and the exam asked questions which were answered in the book, as far as I am aware, the book is only published in English, since I am not fluent in Welsh, it would not matter to me if not published in Welsh, other than it can't be referred to in Welsh laws if not published in Welsh, and if they did, the law would be void.

As to other UK languages I don't know the rules, but this is why we have signs like this and not written signs. But this

uses a double negative so means end of cycling restriction. I selected cycling, as there are so many errors made with signage, I am sure this does not mean cyclist should run over pedestrians or even cyclist have priority. Being a circular sign it is a must, this is optional sign, but we see so many errors with just these simple signs, what is the chance that the instructions in English, Welsh and Gaelic will not have errors?

The number of videos showing multiple solar systems are basically showing the punter this is OK.