Really Need Some advise Urgently

[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?