Really Need Some advise Urgently

[moggy1968]

I've never done a 2 inverter install, but am interested as to why 2 MCBs. That would require 2 meters. When we have discussed this before it was suggested to run the inverters in parallel at the isolator, then to the meter and on to a single MCB.

Looks a neat job, which, as above bodes well. there should be a second AC isolator at the DB, where you would usually also have the meter. I am guessing there is a space issue there.

6 mm cable is almost certainly fine.
The number od DC isolators suggests each array is split into 2 strings. I don't understand why they would do that. I would have thought each array to a single string to the inverter..

personally I would have gone for a single 2 MPPT inverter but thats just a matter of choice.

 

[sedgy34]

I suppose the 2nd ac isolator is there somewhere???? DC isolators could be classed as being a little close to the top of the inverters and so may cause a little bit of airflow restriction, doubt if it would be that bad on an east/west roof though. Gen meter by inverters has never really been our preferred location, especially if the client is elderly and can't climb into the loft every quarter to read the thing!

i agree with the 2nd ac isolator but everything else (behave)

 

[SolarCity]

I've never done a 2 inverter install, but am interested as to why 2 MCBs. That would require 2 meters. When we have discussed this before it was suggested to run the inverters in parallel at the isolator, then to the meter and on to a single MCB.

Not if you connect the meter before a consumer unit supplying the inverters only.

 

[crazygraham]

I've never done a 2 inverter install, but am interested as to why 2 MCBs. That would require 2 meters. When we have discussed this before it was suggested to run the inverters in parallel at the isolator, then to the meter and on to a single MCB.

Looks a neat job, which, as above bodes well. there should be a second AC isolator at the DB, where you would usually also have the meter. I am guessing there is a space issue there.

6 mm cable is almost certainly fine.
The number od DC isolators suggests each array is split into 2 strings. I don't understand why they would do that. I would have thought each array to a single string to the inverter..

Would the system preform better as one large string as aposed to 2 smaller stirngs ?

personally I would have gone for a single 2 MPPT inverter but thats just a matter of choice.

And yes it is very tidy job that has been done in the loft but only after I had stopes them when they started to do it and ask for it to be done very neat with everything planed out rather than just chucked on so with that they removed the inverters and sorted out the level of the back board.
I just wish the panels where as neat as it is the first thing you seen when you turn the corner into my street. I have been promised that all the panels will get removed and the rails will get lowered and levelled to a flawless standard.

I really want to get the photos up for you guys to see and comment. For all I know he used a cheaper fixing bracket or the wrong fixings and that could be why it is so high off the roof.

 

[BruceB]

To answer Moggy's point on why two mcbs, it is because if you only have a single mcb it might be too big to:
- provide fault protection for the cable to a single inverter;
- provide overload protection for a single inverter; and
- you would not have discrimination.

Now you can argue the detail of all those points in any particular situation, but I cannot think of any other reasons the manufacturers would specify it.

Another point on the installation is that it has been in done an over complex and expensive way (probably because that is what they had on the shelf). As it is east/west with neither side pushing out full power simultaneously then a single 5000TL inverter would have done it. Indeed depending on the precise panels used a 4000TL could do it according to sunny design.

 

[moggy1968]

yes, I would argue the detail! Single 20amp MCB would provide adequate protection of all circuits. Discrimination I think is not really a big issue on this type of install. Discrimination is to ensure that for safety reasons in a house you have at least lights or sockets working in a room if a fault causes a shared RCD to trip or is switched off. You could take it to it's ultimate conclusion and say every socket should have it's own RCBO to provide discrimination!
but I wouldn't argue with the rest of what you say, I too would have gone for a single inverter. I suspect the issue of the second hand inverter answers the question on this. As you say, it's probably what they had on the shelf. A 5000TL would work much nearer to it's max for more of the time than 2 3000s, which means greater efficiency.

 

[trev]

My question is why have they used a second hand inverter? Is it all they can afford (which would be an appalling concept) or have they taken it out from somewhere else owing to a fault

 

[telectrix]

a fault, or possibly a non-payment .

 

[trev]

Either way, putting in second hand kit when a customer is, quite reasonably, expecting new is inexcusable

 

[moggy1968]

or decomission?
A company we did some subbing for had to decommission an install and refund the money because they were so rubbish. We spent as much time trying to placate irate customers as doing the electrics! In the end we stopped working for them.

Thats a lot of expensive kit to throw away, so I would guess they have tried to reuse it.
interesting you say the panels aren't the ones you requested. Not related to the inverter issue I'm sure:lipsrsealed2:

 

[BruceB]

yes, I would argue the detail! Single 20amp MCB would provide adequate protection of all circuits.

I agree it would - probably. But it would be specifically contrary to the installation instructions, so you have to ask yourself one question, "Do you feel lucky? Well, do you?" - as a well know police character would say.

 

[Gavin A]

I see no need at all to use 2 separate MCBs as long as the MCB is suitable for both the cable size all along the cable length, and the power supplied by the 2 inverters.

particularly as IIRC DTI guide requires a seperate dual pole isolator per inverter, with the MCB not being dual pole usually, that'd mean both an MCB and isolator per circuit.

to answer the question, yes I feel lucky... well, I feel that SMA's guidance is there to remove the potential for installers doing something particularly stupid, but if using 6mm2 cable throughout and a suitable MCB to protect the entire circuit, and a dual pole isolator per inverter I don't see the problem.

And as we have to protect the circuit from the mains end with an MCB, doing a seperate MCB per circuit would mean either 2 cables from the mains, or an MCB at the mains, the subboard near the inverters, which is a fair amount of extra work and expense for no actual benefit.

 

[moggy1968]

gotta go with Gavin on that. Manufacturers instructions aren't the law, but if you deviate from them you need to be able to justify why, so yes, in a case like this, I feel lucky!!

 

[Gavin A]

same as we've done most of our installs using 30mA RCD on a dedicated circuit, and had both confirmation from Aurora that their guidance was really related to shared circuits, and that for a single inverter a 30mA RCD would normally be ok.

 

[sedgy34]

a fault, or possibly a non-payment .

i agree tel,
Theres probably a genuine reason they had fitted the inverter previously and changed it to reinstall on this job
they could have cocked up on the design etc,been sent the wrong inverter which happens and it was fit for this purpose on this job what ever reason its been working and clocked up 600w its still brandnew.looks a neat install from the pics

 

[trev]

To tell a client that this is new kit and charge for it accordingly(I assume) is appalling.

 

[SolarCity]

606kWh isn't exactly new either. It isn't a great deal of use, of course, but the installer could have offered it at a discount.

 

[sedgy34]

the customer should be asking the question

 

[crazygraham]

Ok guy's here you go. the one photo of the back seems to be a much better install than the way the front has turned out,

 

[whinmoor]

Er, not exactly as smooth as a baby's bum, is it? Why can't the front panels go in portrait as well? Is the front roof the same size as the back?

 

[crazygraham]

it was ament to be portrait at the front as well however it dose overhang onto the neighbours roof by 3cm this was ok with her for the back but not the front.

i would really prefered it to be the same front and back but b4 any discusions they had allready put the rails up in landscape ,

i dont like being able to see the brackets as it really makes it look even worse so i dont know what can be done to resolve this, they will be romoving all the panels in the next week to level it correctly so if you have any ideas on the best way on how to save this i would love to know as im thinking about printing this thread out and giving it to him.

 

[whinmoor]

Overhanging the neighbour's roofspace isn't a great idea. The next neighbour might not be so charitable! It sounds like the surveyor wasn't very good at using his tape measure.

They seem to have kept a 30cm clearance from the edge of the roof as recommended in the regs. The rails and clamps at the back are okish. Maybe the lowest could be a few cm lower but it looks ok and should hold.

Not sure if the cables are tied up to stop them rubbing against the tiles. The fifth photo seems to show a dangling cable.

 

[moospark]

Might be perspective, but pic 5 isoverhanging the gutter a bit, seen a lot worse in the loft though.

- - - Updated - - -

Might be perspective, but pic 5 isoverhanging the gutter a bit, seen a lot worse in the loft though.

 

[Earthstore]

Hmmm, they do look rather high, the maximum the panels should be from the roof tiles is 200mm, not to sure how they have managed to fit them so unevenly though.
Still, they said they will sort it, so let's wait and see!

 

[SPARTYKUS]

Overhanging the neighbour's roofspace isn't a great idea. The next neighbour might not be so charitable! It sounds like the surveyor wasn't very good at using his tape measure.

They seem to have kept a 30cm clearance from the edge of the roof as recommended in the regs. The rails and clamps at the back are okish. Maybe the lowest could be a few cm lower but it looks ok and should hold.

Not sure if the cables are tied up to stop them rubbing against the tiles. The fifth photo seems to show a dangling cable.

Is that a reg.... seen that at several installs (on this road, and for a friend).

Would like to know because when I saw it I thought "thats going to rub"

 

[moggy1968]

it is a requirement that cables are protected from chafing. That means tied up or run in the rails.

The overhang on those middle panels of the landscape ones is far too much, the left hand bracket needs to be further along. The portrait ones look a bit too much as well, need to check the manufacturers reccomendation.

If they have used cross rails to mount the brackets landscape then thats why they sit off a lot. Horizontal rails are installed, then another set of rails on top.
For landscape we only use panels that can be mounted on the short side to get round this.

Incidently, what panels did they quote for and what did they fit?

 

[Worcester]

With all that weight, I do hope you have got a copy of the structural calcs as well, and yes calculations are mandatory, else how does the installer prove that the roof is strong enough.

 

[Eco Deal]

My main worry would be going in the loft every 3 mths to read the meter why put it there thats not right !!!!!

Can the brackets not be adjusted without removing the panels the system mounting system we use you can adjust the brackets easy

 

[crazygraham]

No the panels where rite they where to be sharp 250w and that is what they installed. I did not get a roof report he said that the roof would be fine though I guess having a report would be best I think some can be adjusted without moving the panels but u can't get at the middle.

 

[Earthstore]

You should have structural calculations for the added weight, so you are compliant with building regulations, you should also have wind calculations and a part P certificate.

You do not need to get building regs, but you should be compliant with them.

 

[crazygraham]

hi everyone just an update

well the installers came back yesterday and removed all the panels from the from of the house and leveled all the brackets and lowered them and all i can say is that its a much better job leaves me wondering why this was not done at the start but its fixed now so supose thats all that counts

the inverter is ordered and getting replaced next weekend and the screen on the other on will be swaped out so happy days

i got them to wire the front in one large string to keep the voltage up and the other thing that i noticed is that the sharp panels hav a max amp off 8.3 so 2 strings would total 16.6 and the inverter is onley rated for 15amp is this likley to cause a problem or would it be ok ?

i have been trying to find another 6kw east west split to comprare with but have had no luck would anyone be able to point me in the rite direction ?

 

[Gavin A]

the other thing that i noticed is that the sharp panels hav a max amp off 8.3 so 2 strings would total 16.6 and the inverter is onley rated for 15amp is this likley to cause a problem or would it be ok ?

would I be right in thinking you already know the answer to this question?

i have been trying to find another 6kw east west split to comprare with but have had no luck would anyone be able to point me in the rite direction ?

we have one we monitor remotely. I could probably download some data and send it to you if you tell me what data you're actually looking for. It's in Leeds.

 

[crazygraham]

would I be right in thinking you already know the answer to this question?

I'm sure it should be one large string


we have one we monitor remotely. I could probably download some data and send it to you if you tell me what data you're actually looking for. It's in Leeds.

just looking for daily out puts and to see what times the panels peak at. we have had some nice day here and have not seen either system go above 1.8kw however as one of my inverters is second hand i can look back at the data from the start of the month when the inverter was installed on a different site and it seems to peak allmost every day ?