DC Isolator and PV Warning labels

[billi]

So what Dc-isolators are needed , i thought  the newer Gridtie Inverters have them inbuilt

Are you looking for one that can handle high voltage then ? I guess upto 1000 volt in a grid tie solution ?

something like that ....http://www.santonswitchgear.com/

Is it the law to have them ?

Billi

[Nicedad]

Hi Billi,

UK electrical regulations (17th edition 2008) detail the requirement for dc isolator.  From what I've seen of the Soladin, it doesn't have this facility.  I have read that some people detail the need to the isolator to be lockable. Whilst I see the need for the ac isolator next to the main consumer board to be lockable, I think having the dc isolator also lockable is a bit over the top. 

I'm not particularly looking for a HV specification, just one to handle the voltages likely to be generated by the PV panels. I wasn't sure that the battery switch initially mentioned in this thread would have met these requirements.

[petertc]

I think that the AC isolator need to be lockable not sure on the DC one.

The AC isolator i just got from screw fix.

Like most things when trying to do DIY install it is getting the information on the parts and the installation.

I went for a kit of off ebay but still had to get some other bits because the seller was under the impression that the inverter could be plugged in to a socket! 
After reading the forum here i found the right information and passed this back the to ebay seller.

This forum is a goldmine of information with very helpful people, so having learnt a few things whilst doing my own installation i try to pass on what i have found out when i can and still try an learn from what others have done

[billi]

Nicedad

Here is one for high Volt 500 volt

http://www.solarshop.net/product_info.php?cPath=166_168_273&products_id=2154

and one for low volt ( perhaps is ok for higher volt as well 

http://solarstrom.net/zubehor-batterien/batterietrennschalter-einpolig-1200/600-ampere.htm

Hope that helps

[tony.]

if you are using a circuit breaker or main switch as a dc isolator why dont you buy a lock off kit from reece safety, this compnay sells plastic gizmos that fit to mcbs etc you then fit a small padlock and its now a lockable dc isolator,
problem solved.


As the pv panel  is a source of energy it should have the facility to lock it off to safely work on the invertor.

tony

[Nicedad]

Hi Tony,

I could accept your point if the dc isloator was in a different location to the inverter, but I intend to place the isolator next to the soladin. 

While I intend to comply with 17th edition regulations in order to keep £/watt under control, on this point will only do what is necessary. 

[Justme]

I dont know about the soladin but my Outback FM80 solar controller needs to be isolated from the solar panels before being isolated from the battery bank. In my situation as they are all mounted in the same space I dont see the need to have locks on them. I have fitted breakers to both + & - lines for each string so they can be worked on in isolation.

Justme

[tony.]

the whole point of lockable isolators, is to provide safe isolation.

so if you have a mcb and flick it off, thats not safe isolation, you can go away for a cup of tea and while your away, someone comes along and resets the mcb cause the telly is off, you come back and get a shock.

if the regs say you need to provide lockable isolators and you dont, you have deviations from the regs, so how does this look on a certificate and if someone gets hurt how will this stand up in court.

easy-big fine possibly jail time

tony

[daftlad]

I just had a peek in the regs and there is no need for the dc isolator to be lockable as long as it is local to the appliance, if it is remote it should be lockable (just like a shower switch)
Justme
I may have a bit of a problem with you putting breakers in the positive and negative lines, it sounds like fusing the neutral? if one of the breakers trips but the other one is not switched off then you would test for power, see none because one of the breakers is off and then start workng thinking it was safe. if you use breakers as isolators then they should be 2 pole or the switches linked together.
If an installation is likely to be left during maintenance then a lock is a must to prevent non competent persons switching it on.
I am not sure if they have a dc rating but GEE WIZZ do really cheap lockable isolators
laters

[Justme]

You might have a point apart from

1, both breakers are side by side & next to the controller so its would be easy to see if one had tripped
2, the neg breaker does 2 strings & the wind controller so is not used if just working on one item (this might need looking at, seemed a good idea at the time).
3, even if the neg tripped but not the pos there is no where for the current to flow to as the power shed is remote from the panels & made of wood. All the controllers & inverters are bonded together but isolated from the panels. If I meter from the pos to any point in the shed it does not read any volts except to the neg line. Not tried metering to the 12v neg line but dont think 100vdc would work that way (will check that later)
4, no one but no one but me ever works on the kit (shed is locked).

Odd realy that a single disconect on AC is considered safe yet not on dc lol.

Even more odd is that even with all the breakers off the array is still producing power so the lines are live all the way from the array to the power shed. Could install an outside isolator to counter that. But as it would then be on the roof I cant see it ever being actualy used.


Justme

[daftlad]

Justme
I am not saying that it is not safe just that it probably doesn't conform with regs (regs can sometimes be an ass)
I am not sure about single pole breakers being ok for isolation, the regs say it is ok but they also say that neutral should be considered a live conductor?
Because the pos and neg of panels are not earthed (unlike the neutral) single pole isolation should mean that there is little chance of a shock, but when it comes to isolation i always prefer to go with 2 pole lockable for single phase and 4 pole for 3 phase and i would try to do the same for dc.
I have been trauling the net for isolators that are rated for dc and the only one i found was 180 odd quid, i will ring mk tomorrow.
laters
ps They use 2 pole breakers in France, are they dc rated and are they available in the uk?
pps What about using a 3 phase breaker on the dc?

[Jonbe]

Hi guys i started a new topic AC / DC isolators have a look...

[mallettron]

Here are some I printed off for the panels we use on site

Ronnie

[Justme]

I dont "get" the last one that says to switch of breaker before working on the panels. The panels will still be live unless its dark or you put a cover over them. So working on the solar panel at any time is a live working operation.

Justme

[David]

I may have a bit of a problem with you putting breakers in the positive and negative lines, it sounds like fusing the neutral?

Typically a single phase AC circuit is a two-wire circuit with one wire connected to the earth. A two-wire circuit with neither wire connected to the earth is a different beast, whether it is AC or DC. Both wires can develop earth faults and thus need to be protected against overcurrent with a protective device.

For for these reasons the positive wire of a two-wire DC circuit is coloured brown, unless it is earthed when it is coloured blue. The negative wire of a two-wire DC circuit is coloured grey, unless it is earthed when it is coloured blue.

Table 1 in http://www.theiet.org/publishing/wiring-regulations/mag/2004/14-harmonised-cable-colours.cfm?type=pdf explains the colouring system.