Two inverters, G83/1 and islanding

[devspark01]

This is my first post, so sorry if I go over old ground. I have been viewing the forum for a while and found it very useful - thanks!
My problem: 20 Schott Mono 190s to be split 10 and 10 on roofs of different orientation. One roof is facing south east and the other just south of due west.
Question 1:
Can I use 2 Sunnyboy SB 200HF-30 s and connect to the c/u via one AC isolator and one 16 amp mcb? (I am thinking yes, but wondering about the system rating exceeding the 16amp maximum stipulated by the DNO, G83/1).

Question 2:
And what about islanding? If you have two inverters conected together, how do the inverters know when the mains supply has been lost? Don't they effectively supply each other?
Thanks in advance.
Devspark01

 

[devspark01]

Sorry, I meant two SB2000HF inverters. (Typo).
I guess I could always use two SB1700 inverters?
Cheers!

 

[BruceB]

May I suggest nicely that you read the installation instructions.
They say each inverter must be on its own mcb (page 40).
Max output current of one is 11.4A (page 83), so yes it might output over 16A if all panels in good sun at the same time.
One way you could prove it would not is by doing some calculations based on roof orientations and array size etc.

Let SMA worry about the islanding! Without the real mains connected, the voltage and/or frequency will very quickly go out of limits and the inverters will cut out. Multi-inverter installations are very common at the commercial level.

Regards
Bruce

 

[Worcester]

@devspark01, why not use a SB4000TL, and either set the limit to 16A (if your DNO allows it) , or just get on and do the Stage 2 application?

 

[SolarCity]

Worcester, regarding limiting the SB4000TL to 16A, is this is a simple process? Can I do it from site with a phone call to SMA technical?

 

[Graeme Harrold]

Get a Grid Guard code (always handy) and you can change the settings. DNO usually want to know if the settings are safe, so I always change the installer password (a combination of dialingcode and postcode is good) thus preventing customer access. Its easy to change.........just need a bluetooth laptop and SunnyExplorer

 

[SolarCity]

I met someone from SMA today and he told me that the 4000TL cannot be reduced to 16A. He did say that a 3600TL would be on market by the end of the year.

 

[TedM]

Part of the design requirement that is met under G83 is the anti-islanding aspect of one inverter recognising that the mains is in fact coming from another G83 inverter. The disconnect time still has to be met under these conditions.

The electronics required to accomplish this partly explains why a G83 inverter is more expensive than one you just plug onto a battery.

The same would be required for inverters installed in two adjoining properties (with a common mains supply on the house side of the local transformer) as would be needed for two inverters in a single property.

 

[BruceB]

I met someone from SMA today and he told me that the 4000TL cannot be reduced to 16A. He did say that a 3600TL would be on market by the end of the year.

Strictly he is right. As an installer you cannot limit the current to 16A, but you can limit the power to whatever you like, eg 230 * 16 = 3680W.

Regards
Bruce