Have I missed much + inverter question

[JulianC]

Morning all

Not been on here for ages - basically jacked my job in working for someone else as a PV installer back in June. Set up my own company with a mate and got MCS accreditation at the start of September and am now getting back into it all. Got our 3rd install coming up soon and loving it. Have I missed much, or are we still waffling on about type B RCDs and array frame bonding?


Quick question for those with experience of such things. Currently quoting for a 4kWp ground mount system, about 20m from a distribution board, which is itself about 60m from the incomer. Supply is TT. Planned to fit an SMA 4000TL but heard somewhere they don't like TT supplies. Is this true or did I imagine it?

Cheers

 

[BruceB]

TT should not be an issue in itself. It does mean you need a rcd as part of the ADS protection and the SMA installation instructions say if you have a rcd it should be no less that 100mA. You seem aware of the Type B issue - not a problem for SMA TL inverters. There are regular reports on here of installers having problems with designing satisafctory solutions with ac lengths like your example, so beware.
Regards
Bruce

 

[SolarCity]

I spoke to someone at SMA and they told me that TL inverters can be a problem on installations with high impedances. I have yet to hear what actually IS a high impedance. When I find a figure out, I'll let you know.

 

[JulianC]

Ta gents. Sorted on the 100mA RCD front and aware of the type B requirements. Need to investigate circuit impedances further. Or fit a Fronius

 

[SolarCity]

I'm not sure if it is an SMA specific problem or something that is a characteristic of all TL inverters.