Peak output

[wstevew]

One of those days today where the clouds go and you see a peak, But highest I have seen on mine 3.840kWp east/west system SB4000TL

 

[Earthstore]

All working well now then....

 

[Gavin A]

would I be right in assuming that your roof is relatively shallow?

 

[wstevew]

From a production point of view it always has, just luck it stayed on the roof until they refitted

However all that power down an 2.5mm T&E and SMA say it should be 6mm

PS. Thanks for your advise about the refitting.

 

[wstevew]

would I be right in assuming that your roof is relatively shallow?

Yes I would guess about 22.5 degrees tilt 90 degree azimuth.

 

[Earthstore]

Ah maybe that was why the inverter shut down before, just keep an eye on the AC voltage at the inverter.

 

[wstevew]

Ah maybe that was why the inverter shut down before, just keep an eye on the AC voltage at the inverter.

Its not shut down, just logs DC in Grid before and after feed in on some days.

 

[Earthstore]

Oh yes, forgot that one, have they put an earth on the array yet?

 

[Gavin A]

fwiw, I've just downloaded the data from a 4000Tl we installed last September, which we had bonded to the MET (skylights right next to it) and it has irregular 601 DC grid feed in notices mostly early morning and evening as well, so I really don't see that the bonding makes any difference to it.

 

[wstevew]

No. the top technical man from the installation company is supposed to be making a visit this week to take a look at the system.

I did email SMA again last week and set out how the system is wired etc. Thats when they pointed out the 2.5mm is not enough.

1) They first suggested the event message could be fixed by a firmware update. I said its on the latest firmware already.

They said array bonding is a decision to be made by an installer as every installation is different. Some bond every installation and others do not. (this contradicts their first response a while back).


Their response about the 6mm wire was:-

If 2.5mm cable is used anywhere on the ac side of a SB4000TL the inverter could disconnect frequently when approaching full power. Our inverters constantly measure the resistance of the AC circuit, an if this goes above 1ohm they will stop feeding in. Resistance of a cable increases incrementally in line with the power going through it.

2.5mm cable is allowed by UK regulations on domestic circuits that can operate above 4kw but assumptions are made that this is not a constant load (i.e. appliances such as washing machines switch on and off during their cycles).

A 4kw PV system during a bright day can feed in constant 4kw for up to 6 hours which can put undue strain on a cable if it too small. Hence the 1 Ohm safety limit.

 

[wstevew]

fwiw, I've just downloaded the data from a 4000Tl we installed last September, which we had bonded to the MET (skylights right next to it) and it has irregular 601 DC grid feed in notices mostly early morning and evening as well, so I really don't see that the bonding makes any difference to it.

I couldn't see how it would fix it, but originally SMA said it would. then firmware, and now they say the cable may fix it and that intermittent faults are a process of trial and error. Clutching at straws comes to mind

 

[wstevew]

My installers technical man asked to come and look at the system due to the 601 errors.

He checked the inverter was set up right. I had already said it was but he wanted to see for himself which is fair enough.

He is saying he sees no reason whatsoever why 2.5mm twin and earth would be a problem and changing it will just inconvenience me. He said he would do a bit more investigation.

This may be true but I showed him the email from SMA and said if you don't do what they say you wont get any further with their support if they are saying it could be the issue as it is not to their recommended standard.

I would be grateful as always for your feedback.

 

[Earthstore]

How long is the AC cable run?

 

[dansk]

I suggest the technical man gets more technical then!

 

[SolarCity]

How long is the cable?