Balcony solar PV

[Moxi]

I think there used to be a significant thread at the old place about all this but as Chris N summates the crux of the requirements is not to undermine the protection systems at the consumer unit.

For me this explains why the UK doesn't want the average British punter putting a plug and play panel on their house circuits and has guidelines to this effect.

That said, imagine if someone has a dedicated external socket system that was on heavy gauge wire and which they didn't use for loads for the vast majority of the time.

Moxi

[richbee]

I think there used to be a significant thread at the old place about all this but as Chris N summates the crux of the requirements is not to undermine the protection systems at the consumer unit.

For me this explains why the UK doesn't want the average British punter putting a plug and play panel on their house circuits and has guidelines to this effect.

That said, imagine if someone has a dedicated external socket system that was on heavy gauge wire and which they didn't use for loads for the vast majority of the time.

Moxi

This is a very useful discussion - and my ideas are along this line.
My extra panels will go on the 'Man cave' roof, which has electricity supplied via a 4mm SWA buried cable, to a mini consumer unit, which supplies lights + 1 double socket, which is only used for power tools when I need them.
My plan is for 4x 400W panels feeding a Hoymiles 1600W microinverter. I wasn't planning to use a plug as such, but a wired switch, which would either spur off the socket, or connect to an MCB which could be fitted into the spare slot in the mini consumer unit.
That 'feels' fairly safe to me - but would appreciate the wisdom of the forum

[chris_n]

I think there used to be a significant thread at the old place about all this but as Chris N summates the crux of the requirements is not to undermine the protection systems at the consumer unit.

For me this explains why the UK doesn't want the average British punter putting a plug and play panel on their house circuits and has guidelines to this effect.

That said, imagine if someone has a dedicated external socket system that was on heavy gauge wire and which they didn't use for loads for the vast majority of the time.

Moxi

This is a very useful discussion - and my ideas are along this line.
My extra panels will go on the 'Man cave' roof, which has electricity supplied via a 4mm SWA buried cable, to a mini consumer unit, which supplies lights + 1 double socket, which is only used for power tools when I need them.
My plan is for 4x 400W panels feeding a Hoymiles 1600W microinverter. I wasn't planning to use a plug as such, but a wired switch, which would either spur off the socket, or connect to an MCB which could be fitted into the spare slot in the mini consumer unit.
That 'feels' fairly safe to me - but would appreciate the wisdom of the forum

Your 4mm SWA has a capacity of 36A when buried, your 1600W inverter will give 6.7A so you should in reality have that protected by a 25A breaker. The rest of it sounds fine especially if wired to a spare way in your mini CU.

[AE-NMidlands]

As I am also looking at a similar issue, I did a quick web search.
One answer which seemed to make sense is that if your ring main has a 32A breaker on it - if you have multiple sockets, and you run kettles, toasters, hairdryers etc etc at the same time, your breaker will trip if you go over 32A, which will protect the 2.5mm cable from overheating and worst case melting.
If you add 8A of solar to the mix, you could then run 40A of load through the ring main before the breaker would see 32A and trip, therefore making the circuit potentially more dangerous.

...but the 8A from your inverter will go into the adjacent loads before it gets to the 2 bits of cable delivering the maximum current from the CU/circuit breaker. I can't see how a small extra feed from the far end of a ring can increase the current anywhere on it - assuming it puts power in exactly in phase.
Without the inverter the ring feeds what it feeds, with a supplementary input it still feeds the same stuff but some of the electrons don't come from the CU.
A

[richbee]

As I am also looking at a similar issue, I did a quick web search.
One answer which seemed to make sense is that if your ring main has a 32A breaker on it - if you have multiple sockets, and you run kettles, toasters, hairdryers etc etc at the same time, your breaker will trip if you go over 32A, which will protect the 2.5mm cable from overheating and worst case melting.
If you add 8A of solar to the mix, you could then run 40A of load through the ring main before the breaker would see 32A and trip, therefore making the circuit potentially more dangerous.

...but the 8A from your inverter will go into the adjacent loads before it gets to the 2 bits of cable delivering the maximum current from the CU/circuit breaker. I can't see how a small extra feed from the far end of a ring can increase the current anywhere on it - assuming it puts power in exactly in phase.
Without the inverter the ring feeds what it feeds, with a supplementary input it still feeds the same stuff but some of the electrons don't come from the CU.
A

Yes, that's right. If you aren't using enough to trip the breaker without the inverter, then the inverter won't make it worse.
My understanding is that the problem is in a worst case scenario, where you are using enough load to trip the breaker without the inverter (eg 40A). The inverter supplying 8A would make the breaker see 32A, so it wouldn't trip, despite the circuit being overloaded

[nowty]

That said, imagine if someone has a dedicated external socket system that was on heavy gauge wire and which they didn't use for loads for the vast majority of the time.

Moxi

You mean like my external commando socket on a dedicated 10mm cable.

Its in the correct sunny position for some winter panels.

[Moxi]

Yes thats the sort of thing although in my case its RCD integral IP65 protected sockets

Moxi

[Joeboy]

A frosty morning shows there is more work to be done for shading!




On the upside, the same mighty Enphase Powerhouse has cracked 5kWh generation in very trying conditions.

[chris_n]

As I am also looking at a similar issue, I did a quick web search.
One answer which seemed to make sense is that if your ring main has a 32A breaker on it - if you have multiple sockets, and you run kettles, toasters, hairdryers etc etc at the same time, your breaker will trip if you go over 32A, which will protect the 2.5mm cable from overheating and worst case melting.
If you add 8A of solar to the mix, you could then run 40A of load through the ring main before the breaker would see 32A and trip, therefore making the circuit potentially more dangerous.

...but the 8A from your inverter will go into the adjacent loads before it gets to the 2 bits of cable delivering the maximum current from the CU/circuit breaker. I can't see how a small extra feed from the far end of a ring can increase the current anywhere on it - assuming it puts power in exactly in phase.
Without the inverter the ring feeds what it feeds, with a supplementary input it still feeds the same stuff but some of the electrons don't come from the CU.
A

Who is to say where on the ring the inverter is plugged in? It could be the first socket on the ring then all current is flowing from that point on. As I said earlier it probably isn't a problem unless the ring is broken (you wouldn't know). If you think a broken ring is unlikely ask a domestic electrician who regularly replaces consumer units, they all factor in a couple of hours for fault finding when continuity tests fail. Often when people ease sockets off for decorating one of the wires can be pulled out without knowing.
If it isn't in phase you have an even bigger problem

[Moxi]

All this interesting discussion does bring me to another question regarding something along the lines of the sack barrow mobile power systems of which there are numerous examples on the "tube".

In principle a sack barrow with a box of batteries on the base, a DC hybrid inverter strapped to the handle, and often one or two solar panels to deploy at the side or hinged from the sack barrow and stabiliser steadies fitted - as I say lots of variants.

My question for the forum is - if you had one of these set ups would it be possible at times of the year to charge the battery and then tie that battery in to your house stack - which means because its connecting DC side no need to liaise with the DNO.

Would this upset the batteries ? I ask as its always an option that might just benefit some peoples situation and I don't know about anyone else but a mobile 240V power pack around my garden would be quite useful let alone the chance to supplement the house stack and or plug in the granny charger for the car.

Moxi