Balcony solar PV

[Joeboy]

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

Just strap a 2kW inverter to the barrow. Fully mobile? I added one to the home stack to allow access to that power if we have a cut. I have used it, excellent bit of kit.

[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

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.

Thanks Chris, that's great

[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

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

Yes indeed - the wiring in my house was in a pretty poor state - there was no earth connection and various other problems. When we had the extension built and the external SWA supply to the man cave, I insisted that they replace the consumer unit & sort out the other problems. 2 days of that was them trying to find & fix a break in the kitchen ring main - which then turned out to also feed the bedroom above it.....
Hopefully all up to scratch now

[Tay]

Tks, I knew I wasnt going mad, I'm sure I looked initially and did see it but then checked yesterday and nowhere to be seen..

Just checked again searching for the widest possible search Hoymiles... and boom, seems I might have been a tad hasty, seems there is two Hoymiles companies listed.. mine defaulted to the first which shows a bunch of different inverters..

[Jinx]

My mistake for posting 2kW, you guys homed in on that, of course it doesn’t need to be 2kW, it was merely a comparison that at that power it still remained cheaper than balcony specific. You could of course do it even cheaper with a 1kW version and even under panel if it really concerns.

The output will never exceed the max inverter/panel capability anyway but of course a standard UK plug can be fused down to 5 or even 3A if needed.

In my example I was thinking of a shed type setup, so likely a small radial rather than a ring and anyone doing this is I’m sure capable of managing the system.

Checking a ring for breaks is not exactly rocket science and if it was broken remains a danger, solar or not, it should be rectified by repairing or splitting.

[Joeboy]

Jinx, it is good that we discuss all of this as we aid people we'll never meet by raising their awareness, nice one.

Especially those passing through on a Google search and balcony solar or similar is their 1st foray into PV.

[Jinx]

Thanks Joe, I certainly learn from you guys and I think of myself as above average electrical savvy but always good points raised here.

I repaired a 3.6kW UNO recently and did it all just plugged into the workshop socket and the shed roof panels.

[chris_n]

My mistake for posting 2kW, you guys homed in on that, of course it doesn’t need to be 2kW, it was merely a comparison that at that power it still remained cheaper than balcony specific. You could of course do it even cheaper with a 1kW version and even under panel if it really concerns.

The output will never exceed the max inverter/panel capability anyway but of course a standard UK plug can be fused down to 5 or even 3A if needed.

In my example I was thinking of a shed type setup, so likely a small radial rather than a ring and anyone doing this is I’m sure capable of managing the system.

Checking a ring for breaks is not exactly rocket science and if it was broken remains a danger, solar or not, it should be rectified by repairing or splitting.

The biggest problem with using a 'standard' inverter is the start up voltage is often quite high. Even at 60V start up you probably need 3 panels on the same aspect to start up in relatively poor light. You can get a Growatt 750W that will run at 50V but that is still nearly £300. Of course for some a 'standard' inverter is fine but for many the multiple MPPTs that you can connect single panels to is an advantage.

The whole problem with plugging in inverters is still highlighted in the rest of your post. Yes you can fuse a plug down, yes ring mains should have no faults but they often do and worse still the faults are not obvious. As soon as you start making plug in things available to the general public you have to be sure that they are safe. The general public don't know anything about radial circuits, repairing breaks in ring mains (what is one of them?) IS rocket science to them and they don't have a clue about fuse size. You may be capable of understanding the risks and how to mitigate against them same as some (but not all) on here, in that case crack on as others have done. Personally I wouldn't use a plug, I would change the socket to a FCU or run a separate spur from the socket to a FCU but I would have no issue with connecting a small inverter to a ring I had tested in my own home. I wouldn't fit that for anyone else.
There have been a couple of attempts to sell plug in units in UK and all have been stopped as this does not comply with regs for the reasons discussed on here. FWIW when I have worked with or spoken to sparkies in Europe as soon as they hear about ring mains they think UK is mad, they just don't exist here. Of course in Europe if anyone was to just stick a plug on a bigger inverter then the same overload conditions can apply but you can't legislate against stupidity.

[Joeboy]

I continue to torture myself, check this out!
https://wholesolar.co.uk/products/ja-so ... pYEALw_wcB

[ALAN/ALAN D]

I have just bought another 10 from City Plumbing.
Ive got no Idear why.