Same Crap Different Day

[Easters]

SB 4000 TL on a 2.5 T&E as we have all pointed out in the manual that it states 6mm plus a fair AC run pointed it out once again but same problem as before 6mm is to much money and a waste.
But have spoke to SMA and they said that the guide was out dated and to follow the SMA design guide?
I have a meeting with the Director for SMA UK (with my firm) soon and this is getting pointed out and if I am wrong and 2.5 is fine then I will look like a wolly as I have made a right fuss on this matter.

Any comments welcome!!

 

[northernsun]

Too much money and a waste? Seriously? Thats just mental- not too much of a constructive comment sorry!

 

[fiardor]

Good luck with the SMA meeting and if you could let us know what they say as i have just made my boss upgrade all instals from 2.5mm to 4mm.

And also what size flex from the a.c isolator to the 4000 (or any inverter for that matter) is recommended?

We are currently using 2.5mm 3 core flex.

 

[Easters]

As soon as I know then I will post and hope it clears a few things up.

 

[ExtremePV]

Hi Easters,
The manual states 6mm AC cable for max cable run of 23m. This is to ensure that the max. grid impedance is less than 1ohm. If its higher than this, the inverter can see this as a grid fault and switch off.
If your using a short cable run, then a smalled cable dia. is fine, as long as <1ohm impedance.
I've cross checked this with a Fronius 4.0 TL, and it states 2.5mm cable min.
Hope this helps.
Say hi to Henry.

Ken

 

[Ramjam]

We use 6mm flex and 4mmT&E any regs calc sees that fine, do the volt drop, make sure it's less than 1%.

 

[ExtremePV]

Just been thinking about this again... and given the choice I'd go for the heavier cable every time. Less losses and less heat over a 25yr period. Seems strange to scrimp on a small amount of cable, especially compared to the cost of the rest of the kit.