I’m wondering what is the mechanism the system uses to cut out during a power cut.
If it’s already feeding power back through the grid, when there is a power cut how does it detect that ??
There must be another reason for Islanding prevention other than "protect ESB staff". How come a professional electrician will touch a public electric grid in a power cut assuming 100% sure there will be nothing on the line in the first place?
You only assume that when working in an installation you can physically see and verify there is nothing feeding the wires.
Even if you enforce PV systems to automatically disconnect from the grid there is nothing preventing someone connecting a generator to their mains...
Basically it's a safety issue and done to prevent 'Islanding', which is where if your solar power was still on it could be sent back down the power line and become a safety risk for the ESBN staff working to fix the problem on a line they believe is off.
In fairness you are right though, we need some clarification on the rule with the fireman switches because I was under the impression it was just a requirement for the grant like most SEAI red tape box ticking requirements. I had a quick look but couldn't find anything 100% on it.
😁 I'm lead to believe it's also bliss.
Ignorance is the best defence! I just had to 😂
I don't have access to my copy at the moment but I think I remember reading about it being a requirement, not 100% on that.
"Through these requirements of Part B of the building regulations and I.S. 10101" My reading of that is that they're the requirements of IS10101 and Part B and as such need to be adhered to "under this scheme".
I think it benefit the forum to get confirmation about this because I often see it repeated that the shunt can be removed after the grant is paid.
I don't have IS10101.
Is that quote from the seai (because it mentions "under this scheme" or is it from IS10101 /part B directly?
There was a change in policy around the fireman switch/battery backups in the seai in 2022 ish
I have no issues with seai requiring what they want. Their grant their rules.
Building regs would suggest that a fireman switch is also required. It doesn't matter if the power entering the building is Ac or Dc. I have microinverters which convert the Dc from the panels to Ac pretty much at source, so I have Ac entering the building and by right it seems I should have a fireman switch.
Yeah, no issue at all. It's electricity after all,
Ok.
So in theory I’d have a grid tie inverter at the generation site and it would have the capacity to react and cut power if the mains was off.
Then you have the grid tie at source.. or bring the 3 phase to where you want to go.
From another renewable source 100m away so converting to 240v at source would mean less loss over the distance.
If it's coming in at 240.. from what?
Hydro/wind is a motor spinning. At x voltage, y frequency and z current. 3 phase
Faster it spins more voltage. Also more frequency.
It is then rectified to a stable DC and either with a charge controller (for batteries) with a DC DC converter or a grid tied inverter can also be used.
But if it were already entering the property at 240v an inverter isn’t what would be needed. I was wondering if there were a unit that would take 240v and cut it when there is a power cut.
Hydro for instance would normally be three phase, then rectified into DC, and back to single phase AC with a grid tied inverter.
Last question on this.
Say I had access to another renewable source like hydro and the power was coming in at 240v.
is there a unit I can get to do same process, disconnect the power in event of a power cut ?
it’s just a fanciful notion in the back of my mind. What would I call such a device if I were looking for one.
I know, I was joking. If ever you're asked plead ignorance.
The FUD monger aer out in force tonight 😂😂
For the rest of the time you could have an extension lead to the neighbours keeping the battery topped up.
One neighbour could stump up the 300 a year standing charge for a dozen houses with solar. The powers that be are probably sharpening the feck out of their legal instruments to stop that kind of cord cutting situation arising
Everyone is ignorant about something.
Ignorance is the best defense🤣
Beyond my pay grade that!
I don't believe that's correct, my understanding is that it's to conform to Is10101 and Building Regs part B.
Through these requirements of Part B of the building regulations and I.S. 10101, all domestic PV installations installed under this Scheme must:
• Provide an automatic (i.e., automatically operated by disconnection of the main AC supply to the building) shunt (or interlocked) isolation of the circuit (whether AC or DC, and two pole) from the solar PV modules into the building, as close to the solar PV modules as possible, and a maximum of 1.5m internally from the point of cable entry to the building.
• Where the circuit from the solar PV modules does not enter the building, this point of automatic isolation must be within 1.5m of the solar PV modules. • For ground mounted system the shunt (automatic isolator) must be within 1.5m of the solar PV modules.
• This system of isolation shall automatically isolate the circuit from the solar PV modules when the AC supply is disconnected to the building, i.e., a shunt or interlocked isolation function.
• ‘Shunt’ or ‘interlocked’ isolation of the DC circuit is the only acceptable manner of meeting the Building Regulation TGD B – Fire Safety (2017) for the purposes of this Scheme.
• For the avoidance of doubt the disconnection of the circuit from the solar PV modules must be automatic and operated by removal of AC supply to the building and must not be operated by means of a dedicated switch, pushbutton, ‘fireman’s switch’ or other manner.
• For the avoidance of doubt an isolation of the supply from the PV modules is required in ALL cases, whether micro-inverters, DC optimised inverters, where the inverter is within 1.5m of cable entry or any other configuration is used.
• This system of isolation must automatically reconnect upon restoration of AC supply to the building. A warning label must be applied to the main external AC connection point to the building
It's only needed for the grant though, the North and UK don't bother with them and that's why I had mine removed so the panels work in power cuts.
Found it.
5. Shunt and battery back up The shunt must isolate the solar panel array on loss of mains and cannot be re-energised from the battery backup. The shunt circuit must disconnect the solar array automatically when the AC power is removed and automatically reconnect when the AC is re-energized. The position of the shunt switch must be within 1.5M of the array. This also applies to external systems where the inverter is located outside and the shunt needs to be within 1.5m of the array, taking care to ensure the DC cable is appropriately protected from external forces i.e., use of conduit or SWA cable etc. Where a “back-up system” i.e., battery storage with auxiliary supply is in use, the shunt switch operation must not be compromised and cannot be re-energised from the back up supply. In the event emergency services are called to a property and the mains electricity supply has been disconnected the shunt switch must maintain the disconnection of the solar DC supply and must not be re-energised by the auxiliary output as this will lead to a health and safety risk to emergency services.
You could probably manage it with a modest setup for maybe 7-8 months of the year?
I think you're correct, I'll see if I can dig it out.
Afaik it's an seai rule.
They must be worried that people will get a taste for living off the grid 😂
I don't know for sure but what I was told by an installer, and I read it somewhere too, is that you shouldn't feed the fireman switch with the batteries.
Restores automatically
![Photo of [Deleted User]](https://wd.vanillicon.com/v2/da062963b749703a88f3d03ba7706479.svg)
