New DTI guide

[SolarCity]

We've just found out that the new DTI guide will be with us next Tuesday.

Not sure how much will have changed but it looks like the rules regarding bonding of arrays has been tweaked. Arrays with TL inverter will no longer need bonding. However, arrays which are within the equipotential zone or which can be reach from an equipotential zone (like from a roof window) will need bonding.

I've been discussing this with my partner and we have agreed to change any of our existing installations to bring them in line with these new guidelines. I think it only applies to 9 of our installs so it won't take long to sort them out.

I'd be very interested to hear why the rules on TL inverters have been relaxed.

 

[mmorse60]

Is it going to be in force as soon as we get it or is it going to be a pre-release like BS7671

 

[Worcester]

Guy's don't beat me up again for having access to information...

Anyone could have ascertained this by asking the right questions of the right people at the Segen conference, you just gotta ask ...

They are clarifying the difference between earthing and bonding the array and when either is needed (hooray!) - couldn't get an answer as to exactly will say though

They are also clarifying the needs for RCD's and overcurrent protection for THE CABLE connecting the inverter to the supply (as a PV system with Inverter is inherently a current limiting system) - see my notes elsewhere on the Segen conference (Brum)

Apparently there are lots of other bits of tidying up going on also.

 

[Scott H]

anyone able to share where you can get the new guide from?

 

[Silly Sausage]

Hi Biggs and all you PV guys,

I know very little about PV at the moment but it's something I might consider for my own house in the future. Downloaded the old guide after reading your post, interesting reading.

I've seen some of these installs and I think they look slightly hideous but on the cover of the guide there's a picture of the array elements replacing the actual tiles, that looks really good. Is that a very expensive way of doing it, I get the feeling it is?

 

[Worcester]

@Scott H

You can't (yet) unless you have contacts on the inside helping to write and form it.

It is still undergoing extensive editing. When it comes out I don't expect there to be any major suprises, it should clear up a lot of the ambiguity where 'interpretation' has been allowed.

 

[TJLinks]

Has anyone seen it yet??????

 

[Worcester]

No, it's not finished in the proof reading / final editing phase yet, so it's not publicly available. Only the authors, contributors and editors have access to it.

 

[The Solar King]

I have seen an early draft and expect to get a copy of final draft before too long. With regards to TL, statements from manufacturers will influence this. Trust you have seen attached statement from Power one.

 

[MorganPVI]

From the Power One Doc

Power One Aurora PV and Wind Inverters have build in redundancy for current leakage readings. Detection
has sensitivity with respect to all leakage current components, including the DC component. The leakage
current measurement is performed simultaneously, and independently, by two different microprocessors. It
is sufficient that one of the two devices observes a fault condition to enable the protection and so disconnect
the inverter from the grid.

Am i correcting in thinking this negates the need for earthing the array as it has (in effect) a DC RCD device?

 

[SibertSolar]

Edited - I was about to say that an RCMU is not an RCD/RCCB but I'll stay out of this one for a bit,

Andy

 

[Ian-LS]

Any update when this will be released?

 

[SolarCity]

About 16 months ago, judging by my original post! What an impressively bad piece of information that what.