Solar Query

[Elkcarcx]

Hey! I've been lurking this forum and others of the like for sometime. Gleaning information and taking ideas, hopefully this DIY solar installation can lead me onto the Air to Air units that you guys have installed. But first ill hopefully get this running and send for my successful G99 or G99 fast track application.

But I've run into abit of a pickle with regards to finally turning on my system, i was basically let down by two different Solar installers who were going to come over and give give me well paid advice as per my final earthing requirements/safe practice.

But anyway this is the breakdown of where i am currently.

Victron Multiplus ii 48/5000
Victron 450/200 Solar Charge Controller
Cerbo GX
16xLifepo4 + JKBMS + Class T fuse
ZJ beny 250amp non polarized breakers \

The reason for the 450/200 is the fact that i have mounted my first 10 panels on my shed wired in series, due to the fact the shed is 65 metres away from the main house/inverter. It also gives me scope for 16kwh of solar further down the line if i so choose. As being in the north of Scotland i will need every little help to make the jump to fully electric. The panels feed into an isolator located in the shed, carried up by a 3 core 10mm swa armoured cable into the house. The shed has its own consumer unit fed by the main house consumer unit via an rcbo. The main conundrum for me is the fact that the shed has a metal roof and sides, timber framed with telegraph pole uprights and a concrete floor. I actually have a youtube video of the roof from when i was checking if i actually measured the distance between panels correctly.

[media]https://youtube.com/shorts/zU8pnWxfPI0?feature=share[/media]

I have the Multiplus set up with a separate new consumer unit in the house for the AC 1 out. This will supply new sockets in every room and hallway and eventually the cooker. I've kept the old grid fed consumer unit for my electric shower/shed/old sockets as they will probably never be satisfied unless i go 3x5000. Hopefully i can assist the grid with these loads at the very least via the AC in with a CT clamp.

Hopefully that gives an overview of my situation even if i have jumped around. But the crux of the matter is the earthing situation. I will be connecting to the Grid earth via AC in on the Multiplus as even though i am rural, i am semi detached meaning i could never go truly TT due to proximity. But the chassis of both the Multiplus/Charge Controller/distributor need an earth rod. So how does this tie into the panels and my metal shed while keeping everything safe. I just wanted to ask people who have maybe met with similar issues and have successfully worked through them. A Solar installer told over the phone not to earth the panels, which i can see the validity of. But I'm hesitant to turn it all on on that say so, especially when i have the space/cable and a digger available for good earthing. Ask any and all questions,

[Stinsy]

Why did you chose such a complex and expensive solution to what is a very simple setup? Sounds like you've got c. 4kWp of solar, so a simple off-the-shelf made-in-china hybrid inverter would do everything you need in one box!

There are no worries about earthing if the system is purely grid tied. However if you're on a TN-C-S and you want power in an outage then the simplest thing to do is switch your entire house permanently to a TT. This used to be a pretty exotic thing to do but nowadays with people wanting to utilise the backup power capability of their inverter it is pretty common.

There are other acceptable solutions (eg earth relay that runs your house as TT when on backup power and TN-C-S when the grid is up, or IT) but these aren't worth the complexity. There are downsides to TT vs TN-C-S but these are largely mitigated by having a 100mA time-delay RCD covering the whole installation in addition to the RCD on each circuit.

Incidentally your shed probably should be a TT island and not connected to the supplier's earth.

[nowty]

That’s a mighty expensive charge controller, but it is what it is if you have bought all the kit.

What’s the panel types ?, because you might be pretty close to that charge controllers limit. You need to use the Open Circuit voltage and add a little more say 5% or 10% for really cold startups, especially as you say you are in north Scotland.

Also for G99 applications, they are supposed to be before you install the kit, so don't let slip its already installed.

[sharpener]

Why did you chose such a complex and expensive solution to what is a very simple setup? Sounds like you've got c. 4kWp of solar, so a simple off-the-shelf made-in-china hybrid inverter would do everything you need in one box!

But the 5k Victron gives you 50A passthrough so like I do and the OP plans to you can run the whole house off (inc a cooker) all the time with seamless backup/UPS. Unlike a chinese hybrid which are usually limited to 16A.

There are no worries about earthing if the system is purely grid tied. However if you're on a TN-C-S and you want power in an outage then the simplest thing to do is switch your entire house permanently to a TT. This used to be a pretty exotic thing to do but nowadays with people wanting to utilise the backup power capability of their inverter it is pretty common.

Yes, do this. The Victron has an internal neutral-earth bonding relay to facilitate this.

[Stinsy]

But the 5k Victron gives you 50A passthrough so like I do and the OP plans to you can run the whole house off (inc a cooker) all the time with seamless backup/UPS. Unlike a chinese hybrid which are usually limited to 16A.

Sure. But do you really need 50A pass through? Plenty of the Chinese inverters have 5kW UPS these days, but 3.6kW should be plenty. What do you need to power in an outage? Lights are all LED these days and use bugger all, WiFi Router, TV, Laptop charger… I genuinely can’t think of anything else! Your batteries are gonna last no-time if you try to run your cooker/washing machine or other high-power devices in an outage anyway so you want to keep only the essential low-power devices running.

A wood burner and camping stove can sort your cooking/heating/hot-water needs if there is a very extended outage in very cold weather.

[sharpener]

But the 5k Victron gives you 50A passthrough so like I do and the OP plans to you can run the whole house off (inc a cooker) all the time with seamless backup/UPS. Unlike a chinese hybrid which are usually limited to 16A.

Sure. But do you really need 50A pass through?

Yes, the whole domestic CU is downstream of the inverter, it means in an outage there is no reconfiguration required and the automatic changeover is seamless. No mucking about with torches, changeover switches or load shedding as it has 2x short term overload capability. IMHO well worth the extra cost.

We do have an AGA and a WBS as well.

[Stinsy]

But the 5k Victron gives you 50A passthrough so like I do and the OP plans to you can run the whole house off (inc a cooker) all the time with seamless backup/UPS. Unlike a chinese hybrid which are usually limited to 16A.

Sure. But do you really need 50A pass through?

Yes, the whole domestic CU is downstream of the inverter, it means in an outage there is no reconfiguration required and the automatic changeover is seamless. No mucking about with torches, changeover switches or load shedding as it has 2x short term overload capability. IMHO well worth the extra cost.

We do have an AGA and a WBS as well.

You’re not imagining it correctly at all. You just have your lights and one sockets circuit attached to the UPS, you run the UPS sockets circuit to your few essential devices. Everything else turns off in a power cut. No torches or changeover switches or load-shedding required. This is actually much less effort than with your whole house on battery backup. Your batteries could be exhausted very quickly if your EV was charging, or your tumble drier was running, or some other high-power device was in-use when the power went out.

Sure it is your money (and the OPs) but IMO having your whole house on backup power isn’t the correct solution.

[Elkcarcx]

That’s a mighty expensive charge controller, but it is what it is if you have bought all the kit.

What’s the panel types ?, because you might be pretty close to that charge controllers limit. You need to use the Open Circuit voltage and add a little more say 5% or 10% for really cold startups, especially as you say you are in north Scotland.

Also for G99 applications, they are supposed to be before you install the kit, so don't let slip its already installed.

Open circuit voltage comes to 370 volts. I made sure the panels would fit under comfortably all the way down the -20 + 30s. I will not be turning anything on until I get the application through. And if it gets rejected I'll just limit to 3.6kwh.

I get it's expensive, but I want to be able to add more solar over the years. I've buried four lots of 10mm SWA cable so I can add panels over the next few years. It's full pants on head thinking but I've got the willingness and stupidity in equal measure.

[Elkcarcx]

Thanks for the replies though guys. I agree with both of you on the merit of a cheaper Chinese inverter Vs going full send with the victron. If I had a slightly different use case I would be Chinese inverter all the way.

I will for now separate the shed earth with a TT island as I have the space. Grid tie completely the inverter for the time being as the grid stability is really high that I don't need to run while the power is out. Plus I have the wood burner to keep me warm and fed during the glitches.

While looking in the future to set up a main house TT system that would satisfy my peace of mind.

[nowty]

I've buried four lots of 10mm SWA cable so I can add panels over the next few years. It's full pants on head thinking but I've got the willingness and stupidity in equal measure.

I wish I'd had that foresight as I have dug up my lawn several times and still wish I had an extra spare cable in there.

We like photos when its all in.