Transformerless inverters and type B RCD's

[JulianC]

Currently looking at a 99kWp system, using 6 x SMA TriPower 15000TL transformerless inverters. I've been digging into the requirements for the elusive type B RCD and have found a handy guide from SMA here:

http://download.sma.de/smaprosa/dateien/7418/RCD-UEN103120.pdf

Page 8/11 is interesting in that it states that "all SMA inverters with transformer and all transformerless SMA inverters mentioned in the following are not capable of feeding DC residual currents to the grid due to the circuit design" - it then proceeds to list the majority of SMA's transformerless inverters.

Compare this to 712.411.3.2.1.2 which states "Where the PV converter is, by construction, not able to feed d.c. fault currents into the electrical installation, an RCD of type B.....is not required"

Happy days!

 

[SolarCity]

Thanks for the info, Julian.

And good luck on getting that 99kWp monster!

 

[Markc]

Nice one Julian, Well researched

 

[Banguwangi]

Thats interesting News. Have you installed the system yet? I am doing similar sized systems with the Tripower. Can we now say that if an RCD is not required by 7671 for fire protection on a farm say that no RCd at all of any type need installing prior to the G59/2 relay. If that is the case it will save a lot of time hunting down high current RCDs. What mounting system are you useing? and again thanks for the info

Will

 

[JulianC]

Hi Will

This project is still bubbling away - was off due to structural issues with the buildings but is now back on again and I understand an order will be forthcoming. We are looking to use a clad roof mounting system from ClickCon: ClickCon - Photovoltaik Montagesysteme

 

[mmccx]

what type of metal clad roof is it? Standing seam? Trapezoidal? corrugated?

 

[JulianC]

Trapezoidal

 

[mmccx]

have you seen this?

http://www.sunfixings.com/uploads/media/onto_trapezoidal_sheet.pdf

very very simple soultion, and reasonably cheap

 

[Dmeltd]

Hi julian, how did your system go, i am looking at a 40kw system just now and its the metering i am trying to sort out, what meters can you use that are approved for these size of systems is it a simple case of CT's and schneider electronic kwh meters? or does it have to be landis & gyr type etc.

Also is that bang on re type B rcd's not being required?
That would save some money i have done this before at MCCB 400amps with shunt trips for agricultural and its a pain to say the least

cheers