DC Isolator

[a1colly]

Hey,

Hoping someone out there has got an idea where i can pick up five 100A 1000V DC Isolators. Seem to be running into brick walls with all my usual suppliers.

Thanks

Tony

 

[telectrix]

750V here:

100A 750V DC Isolator - White Solar Systems

 

[a1colly]

Cheers telectrix, had spotted these since posting but still not rated high enough

 

[SibertSolar]

Sorry, have to ask - why do you need a 100A DC rated switch?

 

[Gavin A]

it does seem a lot - 50kWp of panels via a single isolator.

 

[a1colly]

Yeah it's for a 250kwp job in a fortnights time. Last piece of gear to pick up ready

 

[SibertSolar]

Crikey, how many strings are you running in parallel to need such a unit?

 

[jason121]

utter madness,

 

[a1colly]

11 strings in parallel, inverter requirements built the string boxes yesterday to accommodate, drop from the roof structure in 2 core swa 50mm but want to isolate outside of the central inverter for maintainer purposes

 

[Gavin A]

11? I was assuming 10 x 20 panel strings. Unless you're not talking standard 30V, 8amp (ish) panels, wouldn't 11 strings take you over the rating for even a 100A isolator, once you include the x 1.25 derating factor?

Mono- and multi-crystalline silicon modules - All d.c. components must be rated, as a minimum, at: Voltage: Voc (stc) x 1.15
Current: Isc (stc) x 1.25

from http://www.microgenerationcertification.org/images/PV Book ELECTRONIC.pdf

not that MCS actually applies as such to above 50kWp installs, but it'd still be best practice to allow for this if you haven't already?

eta - this is a question more than a statement btw as we've not done anything outside MCS territory so far, so I'd be interested to know if companies are applying different methods above that limit.

 

[a1colly]

No your correct, it does still apply. Panel rating is lower in this instance

 

[SibertSolar]

Make a splitter box instead and fit several din-mount DC switches inside, with suitable fuses for each string?

 

[SibertSolar]

No, scratch that...too much sun

 

[a1colly]

Splitter boxes are on roof with pv string fuses and isolator. Lookin to isolated the feeds once inside the building. Was hoping to find larger isolator a so a to avoiding running even more lines into the building than I already am but looks like I'm going to have to

 

[SibertSolar]

I'll see what I can find on Tuesday