Solar panels during a power cut - what do I need?

[Myfordman]

As a matter of interest, who is buyng the OP's generation? I sell to SSE (or "the Hydro" as we all call it) and also get my supply from them. Pretty sure that somewhere in the conditions for purchasing my generation, there is something that says inverter must switch off/be switched off in event of failure of mains supply. For all the reasons given above.

Grid tie inverters in UK must comply with G83 which amongst lots of other things, shuts down the inverter if the grid supply is out of spec in terms of voltage frequency and (i think,) impedance.
Most generators are not likely to be able to pass any of these tests.
The further problem is that a generator cannot absorb any excess power coming from an inverter when the house load is less than that being produced by the PV panels.

Most inverter manufacturers produce systems that will stand alone but not all of those will reconfigure a GTI into a stand alone one.

 

[n0legs]

So he was putting any number of lives at risk by ignorance and stupidity, and he'd had all this explained to him... you must need the patience of Job sometimes.

I continue to be really impressed by the tenacity of your lot in the depths of winter.
.

In a word, yes.
It was for him an attitude of "my lights are on, who cares".
Patience is not something I suffer with :lol:. I've learned to daydream at a moments notice, so they have their say then I have mine :lol:

No, seriously you learn to tune out the static, get to the point as soon as possible and then offer up what is going to happen. It's a rewarding job but at times extremely frustrating.
When the manure hits the rotor and the "call to arms" is made it still impresses me what the boys can achieve in some god awful conditions.

My old mentor, Jack Hammer Lewis, had a bag full of sayings and comments.
One night past midnight, wind howling and the rain trying to peel the skin off your face, he came out with
"It's worse than being in the bloody army ,,
"Why's that?" says I.
"Well lad, if the weather's too bad they cancel exercises on Salisbury Plain" :lol:


Thanks for the appreciation and comments ETV =D>

 

[n0legs]

Pretty sure that somewhere in the conditions for purchasing my generation, there is something that says inverter must switch off/be switched off in event of failure of mains supply. For all the reasons given above.

Grid tie inverters in UK must comply with G83 which amongst lots of other things, shuts down the inverter if the grid supply is out of spec in terms of voltage frequency and (i think,) impedance.
.

Gents, I think Wuffles has sussed this out. Hence his idea of connecting his genny to "trick" the inverter into believing all is fine and dandy, so to continue to produce and obviously run the homestead.
If I've missed the point or just plain old got it wrong, then I do apologize

 

[RogerS]

If Wuffles consumer unit is anything like ours then he already has a double-pole isolator built into it.

On the rare occasions that we get a power cut of any meaningful duration (and I have to take my hat off to Western Power Distribution because since they took over such faults are virtually non-existent round here) I simply turn off the isolator and power up my 6KW generator that comfortably powers the entire house.

His main problem will be going round the house turning off everything until his solar panels have been fired up as I doubt that his 'priming electric source' will be man enough to power them if, for example, the fridge compressor kicks in at the same time that he is firing up the panels.

 

[Wuffles]

I had walked away from this, but if people are happy to chat about it, I'm all ears.

From my meter I have two sets of tails going to two different consumer units. One for the house CU, one for the heating system CU - 2 x Heat Pumps (1 16kw & 1 9kw (output)).

The outbuildings (and the solar array) are coming from the house CU on a separate breaker which feeds a smaller CU in the workshop. So theoretically lots of things could be isolated, but the solar being on a separate breaker, well, I'm not sure if that's a help or a hindrance.

 

[RogerS]

Are you saying you have

meter > house CU > and one way goes > breaker >>>>>>>>>>>workshop CU and solar panels ?

If so then my plan will work - you just turn off the main breaker on your house CU.

But...if you want power to your heat pumps from the solar array as well then you are stuffed unless you get an electrician to put in an isolator after your meter which then feeds a couple of Henley blocks which then feed the two CUs. In this instance, when you have a power cut you keep the isolators on ...on both CUs but turn off the new isolator.

 

[Wuffles]

Heat pumps would eat the 4kW off the panels alive, I'd be happy to keep that separate.

Where's the excess power go though?


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[CHJ]

.

Where's the excess power go though?..

There isn't any, there is only spare capacity, no different to water in a tank, it only flows if you turn the tap on and draw the water off.

There may be problems with the stability of a generating system if it does not see a big enough load for its regulating circuits to maintain stability but it does not produce output current unless there is a demand.

No different to your solar panels producing a voltage at their output, if the invertor is not active and taking current then they don't supply it.

 

[Wuffles]

This will probably help massively then? 'Scuse the mess.

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[n0legs]

This will probably help massively then? 'Scuse the mess.

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Trust me I've seen worse, you ever been to the Gurnos in Merthyr?? :lol:

If that's the only supply to the house/installation, the isolator you need to stop a "back feed" into the mains is the white one right in the middle.
I can't speak for the rest of your installation, and wouldn't to be honest, but that's the one to take you "off grid".
Ignore the bit about WPD Property printed on it, you may operate the switch if you wish and that's official 8)


I have seen in the past many ways of connecting a generator. One that stands out, is one guy had a 64A Commando style socket connected via an isolator into a service block (one unit, usually rated at 100A, but doing the job of those pair of Henley/neutral blocks in the picture).
He would isolate the mains and plug in the generator with a dedicated lead, it was IIRC a 10Kva genny, so well worth all this effort.

 

[Wuffles]

I meant the snail in the bottom left of the picture, but now you point it out, there is a switch there

So, during the apocalypse, flick that off, fire up a generator to get the solar array onlne and turn on circuits to suit? Not sure if the question was ever answered, but do I need to leave the generator on to power the inverter or would it become self powering once it's all been jump-started.

I'm not going to do this by the way, unless WPD were to send a text saying power's going to be out for more than a few hours anyway, it was all theoretical and got a bit out of hand.

 

[RogerS]

Well if you're all geared up and ready to go then you can, in certain circumstances get mega-brownie points from SWMBO (if you have one). Few months ago, she was up around 5.30am to get ready to catch the early train to London for an appointment that she couldn't miss.

5.35am the lights went out. And didn't come back on again. So not a self-resetting fault then. Quick call to WPD and they're on the ball as usual..."Estimat d time to repair - two hours'.

5.40 am - generator fired up, house on full power, so she could get ready to catch the train....MEGA-brownie points.

 

[Wuffles]

I'll keep my eyes peeled for a generator.

Thanks everyone.


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[Eric The Viking]

I have seen in the past many ways of connecting a generator. One that stands out, is one guy had a 64A Commando style socket connected via an isolator into a service block (one unit, usually rated at 100A, but doing the job of those pair of Henley/neutral blocks in the picture).
He would isolate the mains and plug in the generator with a dedicated lead, it was IIRC a 10Kva genny, so well worth all this effort.

That's a really good idea as it's inherently safe, too - no danger of back-feed or bits going live by mistake.
It's like my small-scale arrangement for the study ring.

But re-reading what you said (above) did that mean a pin-to-pin lead was involved somewhere, or did he simply insert a 64A plug+socket downstream of the meter? I'm hoping the latter, as it's foolproof and easy to manage:

                                            [64A socket]-[meter]-[e'board fuses+incomer]
                                          /
[consumer unit]-[64A plug(chunky tails)]         (goes to either, NOT both!)
                                          \
                                            [64A socket]-[genny]

Tthat ought to be safe and straightforward, but without automatic switchover (which is a lot more expensive than two sockets and a plug!).

 

[Eric The Viking]

I'll keep my eyes peeled for a generator.

With the plug + socket arrangement above you ought to be able to use your solar system instead of a genny (with a small inverter to frequency-lock it to, but that could be completely independent, probably). The difficulty would be arranging to disconnect it from its normal arrangements and put it back afterwards, as AIUI, it's "downstream" of a bi-directional meter.

I bet there are "people wot kno" in your neck of the woods - the folks on the Levels are nothing if not resourceful.

E.

 

[n0legs]

I have seen in the past many ways of connecting a generator. One that stands out, is one guy had a 64A Commando style socket connected via an isolator into a service block (one unit, usually rated at 100A, but doing the job of those pair of Henley/neutral blocks in the picture).
He would isolate the mains and plug in the generator with a dedicated lead, it was IIRC a 10Kva genny, so well worth all this effort.

That's a really good idea as it's inherently safe, too - no danger of back-feed or bits going live by mistake.
It's like my small-scale arrangement for the study ring.

But re-reading what you said (above) did that mean a pin-to-pin lead was involved somewhere, or did he simply insert a 64A plug+socket downstream of the meter? I'm hoping the latter, as it's foolproof and easy to manage:

                                            [64A socket]-[meter]-[e'board fuses+incomer]
                                          /
[consumer unit]-[64A plug(chunky tails)]         (goes to either, NOT both!)
                                          \
                                            [64A socket]-[genny]

Tthat ought to be safe and straightforward, but without automatic switchover (which is a lot more expensive than two sockets and a plug!).

What he definitely had was one of the older type fused isolators fitted in his meter tails between the consumer unit and meter. These fused isolators were/are used when the meter tails are excessively long. I'll see if I can get a picture.
When the mains failed he would open this isolator and connect the genny.

With the tails from the isolator on the consumer side these were split by the service block, one set of tails going to the consumer unit and the others going to another isolator directly above the commando socket.

It was definitely a socket he had fitted as it was the only thing I could find fault with. The fact of having a lead with a male plug either end for connecting the genny. This obviously brings the issue of potentially having the lead connected to the genny when energized and bare pins in the plug where contact could be made. Or vice-a-versa having the plug in the mains and a live plug at the genny end.
I could see his rationale, he deemed having a socket at the mains end a better choice. No bare contacts if the mains were on and it's isolator still in the closed position. There was more likelihood of someone other than he being in with the meters and consumer unit. To be honest you could see this guy was no dummy and was extremely, excuse the pun, switched on.
Overall it impressed me. It had been thought out and was safe. Someone with a good knowledge and who had got themselves into a sort of procedure could carry out the connection and disconnection safely. It beats hands down many of the methods I've seen #-o

 

[RogerS]

Yup, I had to do something similar on my generator as it is fitted with a socket. So I have a flying lead fitted with a male plug that feeds back into my mains BUT via a double-pole isolating switch. And just in case some eejit turns that switch on by mistake, the male plug is safely locked away inside its own little wooden box. And I have the key.