Question regarding fuse board

Ginger83 · 04-10-2022 2:36pm #1

The main fuse board is in the house but there is a smaller one in a shed fed from the main one.

Does a solar pv system need to be wired to the main fuse board? I'm thinking the shed is behind the house so wiring would be out of sight

bullit_dodger · 04-10-2022 3:27pm

It depends is the best answer people here can give you. The main issue is the guage (thickness) of the cable supplying the secondary small fusebox. Your inverter for the solar panels can output 6kw, and that requires a fairly sizeable cable going back to the main fuse box. You could burn out your exissting cable and potentially start a fire if it's not rated for the current.

A spark would be able to tell easy enough, but I suspect you'll be routing a new seperate cable back to the main fusebox

Markus Antonius · 04-10-2022 3:35pm

I also have this exact same question and am hopeful that because the shed fusebox is catered especially for electrical equipment that it would be able to handle solar too, but probably best to get a sparky to confirm.

If everything above board though, all the household appliances/grid would then draw from the shed fusebox via the main fusebox on sunny days I gather?

graememk · 04-10-2022 4:13pm

My Inverter is 2 consumer units away from my main consumer unit.

I do have 16mm2 going to them though.

Main consumer unit - Meal Shed consumer unit - Barn consumer unit - Solar inverter.

Its a straight inverter, no batteries so I didnt have to run CT's back to the main grid.

I know some installers are using a wireless transceiver (LoRA i think, Its transmitting the RS485 signal, not Raw CT signal) if they cant bring back a cat 6 cable for hybrid inverters.

The grid tie inverters always try to slightly exceed the grid voltage so anything that is not used by the house, is exported/put into batteries.~

House always gets priority.

slave1 · 04-10-2022 4:33pm

16mm2, lol, future proofing!!!

Ginger83 · 04-10-2022 4:34pm

https://www.boards.ie/discussion/comment/119700395#Comment_119700395

https://www.boards.ie/discussion/comment/119700599#Comment_119700599

My issue is that the front of the house faces almost south but it's an old building with thick stone walls. Getting cables back to the main board would be a nightmare and they would be seen.

If we considered a smaller system the panels might possibly fit on the shed roof (southwest) and then put everything in the shed.

The fuse board in the shed currently runs power for light, socket, kerosene burner, water softening system and robot lawnmower.

graememk · 04-10-2022 5:11pm

https://www.boards.ie/discussion/comment/119700687#Comment_119700687

I not digging up the street again, Have a couple of cat6 over there too.

Also have a 2*2.2kw motors on a crusher down there, so we needed the extra power (you should see the current spike when they start, even under no load, about 100amps for a split second)

https://www.boards.ie/discussion/comment/119700693#Comment_119700693

All depends on what cable size going out there.

Its likely only a 2.5mm2 cable, esp if its an old building.

Ginger83 · 04-10-2022 6:12pm

https://www.boards.ie/discussion/comment/119700834#Comment_119700834

Is there a minimum size the cable should be?

The house was fully rewired in 2011/2012 and the shed built around then also.

graememk · 04-10-2022 6:49pm

https://www.boards.ie/discussion/comment/119701135#Comment_119701135

All depends on load, an indication of cable size is what size is the breaker that goes out there, if it's 32 you may be good

Ginger83 · 04-10-2022 7:21pm

https://www.boards.ie/discussion/comment/119701273#Comment_119701273

I have located it but I'm not sure. The trip switch has a few numbers on it. If I have uploaded the photo correctly it's the second last one on the bottom row.

20221004_190841.jpg

Jonathan · 04-10-2022 7:44pm

https://www.boards.ie/discussion/comment/119701391#Comment_119701391

That's a 20A MCB, so given the length is likely 2.5mm². You could probably fit a 3kW inverter on that cable, but I put any more on that.

Ginger83 · 04-10-2022 7:52pm

https://www.boards.ie/discussion/comment/119701466#Comment_119701466

Fuse board to fuse board is around 45-50 feet

bullit_dodger · 04-10-2022 8:09pm

It's not so much distance of the cable, but the current going over it. As the lads above have said, that's a 20Amp breaker. So to avoid it tripping, I'd probably stay under 18Amps. which is (18 x 230) ~ 4.1Kw watts. So your max inverter size really is a 4kw with the existing cable.

You might get lucky though and the spark used a heavier cable than the 20A breaker alludes to, but that would be unlikely. Most electrians won't do that as heavier cables are more expensive. As in there's no need to spend money on a cable which doesn't have the load.

But don't be discouraged, most sparks are used to this type of stuff and can come up with a solution when they see your place, or put the inverter in the attic of your house etc.

Ginger83 · 04-10-2022 10:06pm

https://www.boards.ie/discussion/comment/119701572#Comment_119701572

Thanks. If the cable is as you and others have said I take it that I'm aiming for a max 4kw system subject to discussing with the installer?

Markus Antonius · 05-10-2022 12:42pm

https://www.boards.ie/discussion/comment/119702205#Comment_119702205

I'm hoping in my situation that if the cable is undersized for the solar system I'm planning on putting in (6.4KW), that the electrician will be able to use the current wire to pull through a thicker one without having to dig up anything.

Ginger83 · 05-10-2022 2:18pm

https://www.boards.ie/discussion/comment/119704029#Comment_119704029

Yes it would be great if that works. I am happy enough with a smaller system to start with, it will help us reduce the bill a little.

What is your views on a battery? Some do, some don't

ACCAman · 20-12-2023 2:42am

I have a similar question relating to the topic on this thread, so I'm going to reopen it instead of starting a new one.

We currently have a small enough 3kw Huawei system setup with a 5kw battery and inverter in the attic of the main house.

I'm looking at ways to expand it so that I can cover more of the power that we use. I'm thinking about using a cabin that we have at the end of the garden about 15-20m from the house. Looking at a ground or roof mount in the vicinity of the cabin away from the house where there is more room.

The cabin is newly wired properly in 2022 with it's own consumer unit with space in it and from looking at the invoice looks like it was done with a 10mm SWA supply cable. It says overcurrent protection 40 amps. It also says main switch 63a.

Would I be able to connect another inverter, switches and panels to the consumer unit in the cabin?

If I did this, would the power generated on the new panel array at the cabin send power back to be used in the house?

Could the power generated by the new panel array also charge the battery and feed back excess to the grid or would the new inverter need to be cascaded with the other one to do this? I think the inverters would be a bit too far apart to cascade plus there may be additional extra wiring which would be tricky. The cabin was wired through a trench under the garden which is not really accessible any more.

last question is Huawei related, would I be able to see the generation and all of the usual details from the new array included in the overall figures in the app? Inverter not cascaded for this obviously.

Thanks in advance, I've been looking online a lot for the answers to these questions but they're not easy to find.

graememk · 20-12-2023 10:56am

Inverters don't need to communicate, your for put another 3kW inverter and stay within the NC6.

It can be connected into your shed consumer unit without issue.

Some inverters can take the excess from other inverters and put it into the battery (as long as it's within the charge rate of the battery. Sofar, solis, sunsynk can do it for sure. But I have no experience with Huawei.

Worst case scenario is that 100% of the generation from the Huawei inverter will go into the battery, and the second inverter will do the house load and any excess is exported.

Ginger83 · 25-02-2024 12:18am

https://www.boards.ie/discussion/comment/121516664#Comment_121516664

I'd love to hear if you followed up on the cabin idea

Question regarding fuse board

Comments