how to isolate Solar PV system?

[ForeverYoung]

Looking to do some structural remedial work on an old shed (termites).
Looking to know how to isolate the system for safe work in the surrounding area/stud frame etc.

The shed has Solar Panels on its roof and inside is an inverter and mini switchboard.
Electrics run from the shed underground (barely) to the house where there is a main switchboard.
The meter is on a pole at the street, just 2 switches there, one main, one house.

pics of shed inverter:
IMG_20251111_095042.jpg

IMG_20251111_095146.jpg

There are also solar panels on the house roof and another inverter inside the house (with its own mini switchboard).

pic of house switchboard:
IMG_20251111_094545 - Copy.jpg

I know nothing about them (installed by previous owner).
The inverter display panels don't really tell me anything. Green light indicates on.

In the past with power outages everything resumes as normal - tho I haven't thought to look at the inverters during power outages to see if anything is happening there.

So, to isolate the shed Solar system I could

1. just turn off the inverter
2. and also the PV array switches?
3. and also one of the switches on the main board.

If I leave everything on and just turn the 1 switch off at the main board then the light on the inverter should go off?
Just trying to figure out how I decide which switch on the main board is for which inverter.

Is there a particular order to turn them off, back on?

[ErrolFlynn]

Looking to do some structural remedial work

I can't provide electrical advice, but I'm wondering about the extent of the work you need to do. Can't you work around things? For example, if you need to remove a few posts, consider supporting the roof with acrow props until you get the new post in place.

[ForeverYoung]

... I'm wondering about the extent of the work you need to do...

the shed is old, but functional.
when the idiots installed the inverter etc they built a new frame for it inside the existing hardwood frame using new untreated pine.
needless to say, termites have made a beeline to it.

plan is to remove external and internal cladding.
assess damage.
replace pine frame and reattach solar gear to a new frame.
replace cladding.

during the process there will probably be copious spraying of termite treatment in the vicinity of above said electrical wiring - best if it is not active me thinks.

[ErrolFlynn]

Best wait for a sparky to make a comment.

I've tinkered with things at home. (I have certain skills.) However, if no one chips in, my process goes along these lines: switch everything off (for fear of dodgy wiring), and I've even pulled fuses out as well. Then, before touching any bare wires, I've shorted them with a pair of pliers or flicked them together, just to make sure there's no power coming through. Then, on the odd occasions when I've known which fuse powered where I was working, I'd often take the fuse with me and put it nearby where I could see it. Right next to the job, usually. For my personal well-being. (Ceramic fuses are still around.)

[ForeverYoung]

I've tinkered with things at home

me too.
happy to just isolate a circuit if that is more convenient.

in this case it may take a while to remediate the termite damage in the vicinity of this one Solar PV so I would prefer to leave everything else operational.

once it is all apart I made need to engage a solar tradie to put it all back together again.
depends on what I need to demolish I guess.
at the moment I am hoping I can leave it all wired up and just hanging there while I reconstuct around it.

[ForeverYoung]

turned off the RCD Solar Supply Main Switch on the house switchboard (N4)
turned out to be the right one.
Inverter in shed went from Green light to Red (fault).
the red must be powered by the solar panels?

turned it back on and after a few minutes Inverter went from completely blank to Green light.
this would pretty much simulate a grid power outage I guess (frequent occurrence here).

so, to stop any charge/current from the panels would need to turn off

• Inverter Switch
• and array switches - looks to be 4 RCD types and a smaller one in the middle.

[droog]

Your main issue will be even with all breakers in the off position the panels will still generate output, it just won’t be passed through the inverter and on to the grid.
End result is there will still be things that can potentially bite with it all turned off.

You stated you will need to engage a trade to reinstall, I suggest engaging a trade to assist make safe and remove any components, then reinstall once repairs are complete.

[ForeverYoung]

Your main issue will be even with all breakers in the off position the panels will still generate output, it just won’t be passed through the inverter and on to the grid.
End result is there will still be things that can potentially bite with it all turned off.

You stated you will need to engage a trade to reinstall, I suggest engaging a trade to assist make safe and remove any components, then reinstall once repairs are complete.

thanks for that, that's what I needed to know.

[ErrolFlynn]

When my solar panels were being fitted, and before the job was finished, I climbed onto the roof to check out what was going on. Actually, I wanted to see how the panel mounts were being attached to the house. I'd heard of some rough jobs. As it turned out, a nice job was done. Anyway, while up there, the guy demonstrated how the panels were working. He took a couple of the wires from a panel/the panels and shorted them, and there was an arc which was sustained as the two wires were held a short distance apart.

My gut feeling at the time was that I'd rather he not have done that. Seems to me it was a bit like holding your foot flat to the board on the accelerator of your car while in neutral.

Anyway, it goes to demonstrate what Droog was saying. Short of covering the panels with a heavy canvas tarp, there is quite a punch lurking in them while the sun shines. Actually, I was surprised there was any spark of significance, thinking them to be relatively low voltage output. But it was a damn healthy spark (thick) and was jumping a distance greater than expected.

[ForeverYoung]

Short of covering the panels with a heavy canvas tarp, there is quite a punch lurking in them while the sun shines

yes, but it does seem odd.
during installation they must be made safe somehow?
maybe just insulated terminators on the wires until hooked up.

I wanted to see how the panel mounts were being attached to the house. I'd heard of some rough jobs

yes. this is another problem I have on the house panels. roof is 45deg.
and the panels are mounted too close to the roof on horizontal struts so they have become a litter trap.

[ErrolFlynn]

a litter trap.

A fire trap too, maybe. I guess you go up there every now and again, like when gutter cleaning, and get rid of the leaves.

Actually, it's a good idea to get up close and personal with your panels. I've been at mine with a hose and squeegee sponge & window cleaner type thing every now and again. I was surprised by how much lichen grows on them. Though, 45deg sounds like a task for a cherry picker, or someone with mountaineering experience.

[droog]

yes, but it does seem odd.
during installation they must be made safe somehow?
maybe just insulated terminators on the wires until hooked up.

Panels are connected in parallel or series or a combination of both. In parallel connection voltage stays the same current flow is added together. In series it is the voltage which is added together.
While each panel may be fairly low, lets say < 50V what is fed to the inverter may be hundreds of volts depending on the panel configuration and inverter you have.
Disconnecting a single panel the individual panel connectors may only be low potential, but exposed connectors from the rest of the chain may still have a high potential voltage.

If you are not familiar with these systems and how it is all connected then I advise getting someone in that does understand them.

[HavinaGo]

thanks for that, that's what I needed to know.

Droog is spot on but if you are lucky there may be an isolator on the string of panels on the roof... There is on the 2 systems I have had anything to do with in Vic.. one installed in 2011 and the other in 2022... But no guarantee as some systems do not have isolators on the roof. AND even if they do, there were lots of stories of recalls for faulty isolators... Also the full panel voltage is still in the string.... So care needed.

I clean gutters and panels at dusk to limit risk.... I'm not up at dawn and dew is not helpful.

Tarps over the panels is a good fallback but care still needed as no light is what's needed not blue or green...... Covering one panel in the string limits the current the total string can deliver BUT full open circuit voltage will still be at the ends of the string.

DC is nasty at higher voltages as it is hard to stop current flow once it gets going and you don't want to be in the middle. AC changes polarity 100 times a sec so switches use that to break the arc, but DC just keeps on!

Go carefully and all the best with evicting the white munchers.

David

[ForeverYoung]

Droog is spot on but if you are lucky there may be an isolator on the string of panels on the roof...

doesn't appear to be.

Go carefully and all the best with evicting the white munchers.

have tried to get solar 'experts' out to turn the system off.
no luck so far - any tradies hard to get these days.
will try for a local sparkie.
been too hot here to do anything much.