Solar for Beginners [ask your questions here]

At the moment I have a double socket beside my inverter, (you have a picture of it from a PM) I set up all my basics to be able to run off the battery during a power cut. Router, cctv, microwave, toaster, kettle and such like off an extension lead. The changeover switch either manual or automatic will power certain circuits like sockets and lights up to a certain load in the event of a power cut.

The SEAI have inspected some installations with changeover switches and said nothing so I believe when they were fitted but I heard of a few where they had to be taken out. So I just got the double socket until a possible inspection passed and will be putting in the changeover switch. When getting your install done get a double socket or ask your installer about the changeover switch.

Yeah thats the idea - you can plug in and have power in the event of a power cut. I found it quite frustrating last night knowing Id a 50% full battery sitting there that i couldnt use.

I have the socket coming from the EPS for now, installer said the SEAI wouldnt approve anything else. I intend to change it after grant approval.

Once your grant money is in, the installer should change it for you.

Why is it dangerous? What are the chain of events? (I realise youve given an explanation, but given that this is the solar for dummies thread and I am a dummy with solar).

Depends probably how it's wired.. the panels are put on wires to the invertor called strings.. if you have panels on front and back if house or get sun at different times of the day they are put on different strings back to the invertor.. usually inverter can take two strings so you are probably fine

I'm not sure to be honest.. others will comment I'm sure. Even with 4.8kwh panels I'm not sure you'll see that much from them so a 4kw inverter may be fine.. I've 4kwh on my south east roof and I get at best 2.5kwh on a sunny day.. I expect that will improve as the sun is higher in the sky outside of winter..

Basically you need low resistance to earth for your mcb to operate in the event of a fault. Your neutral cable is what's called a protective earth neutral and by switching that you're left with a high resistance to earth. So your house is now in a scenario where under certain conditions your mcb's will fail to operate.

As I said I wouldn't have this setup in my own house. I have a backup generator and inverter wired to a manual changeover switch but I didn't switch the neutral.

https://www.ecdonline.com.au/content/electrical-distribution/news/the-dangers-of-switched-main-neutral-conductors-1150404969

So it f you have an earth rod this isn't an issue?

There're two "earths" coming in to a house. One is the pen conductor which is connected to the esb neutral in your meter cabinet. The other is the earth rod.

Your main earth is actually the one going to the meter cabinet. This is a low impedance earth. The earth rod impedance is quite high in comparison.

Having an earth rod will not protect in the case of having a switched neutral.

There is the possibility of anything connected to earth becoming "live". Think metal bath, sink, copper pipes etc.

Trying to calculate the sqm of my roof to figure out how big a KWP system it could fit, its a small steep roof on a 3 bed semi and it has a velux window in the middle of it takng space. If I know the sqm of the ground floor and the distance from the front of the house to where the front roof stops (by measuring along the gable) and I know the approx angle of my roof (40-45 degrees) is there a formula I can apply to get the size of the roof in sqm?

Also am I correct to say that in general 1sqm of panels equates to 150 watts? Is that the limit or are there special panels out there that will give you more watts per sqm?

Eyeballing the roof space and accounting for the velux window I reckon there is probably 15sqm of space for panels which at 150 watts per sqm would give me a system size of 2,250Kwp which seems a bit small. Im looking to estimate how many kwh a year that could deliver,a pointer to a good calculator would be welcome.

Quoted for a 4 kwh system with a 4kw inverter but on day if install I asked to fit 2 extra panels....

My understanding is that Australia uses a tncs system same as here, I'm open to correction on this but the point still stands regardless.

When you switch the neutral you lose the low impedance path to earth which is required for an mcb to trip in the required time, your earth electrode impedance can be quite high.

In certain circumstances an rcd may not provide protection as current must flow to earth, that's how the imbalance occurs. The other thing to consider in a tncs system is that you have circuits that don't have rcd protection, ovens, lights etc. Rcd's can't always be relied on anyway, most rcd's here are type AC which can be blinded by dc currents or you may just have a faulty one. If you have a type AC rcd in your distribution board get it replaced as soon as possible, modern appliances can cause this blinding as well as EV's and PV installations. Type A is now mandatory and type B in certain circumstances.

All I'm saying is to be very careful with changeover switches, is10101 isn't very clear on whether or not the neutral should be switched and is open to interpretation, I'll try to post the rule on this later.

I would get advice from an electrical engineer before having one installed as most electricians just blindly switch both conductors.

Yes I know I got what I ordered, my question really was how does having a 4kw inverter affect my production as apposed to a 5kw inverter?

You will only be able to use the 4kw generated not the 4.8+ you could possibly be able to use at peak production. That is why my previous post advised to get the 5kw or 6kw inverter depending on if you intend expanding in the future.