Snuffleupagus Posted December 27, 2021 Share Posted December 27, 2021 Greetings people of the forum! I have been planning my solar power system for a while now and purchased most of the components. The installation is 100% DIY, so I am going solo on trying to figure things out. Now I am at the point where I need to map out how the wiring works... Here is my current attempt at a wiring diagram: Since the forum contains members far more experienced and knowledgeable than I, I'm throwing this out there to see if anyone has something to add before I go ahead. Am I missing something important? See something that won't pass CoC? Any comments will be appreciated. In the diagram I omitted the main db circuits (lights, plugs, etc.) since they are already there (and approved compliant) and won't be changed apart from splitting the db into essential and non-essential. I was also wondering about needing to split the neutrals for essential and non-essential circuits. The inverter manual wasn't really too clear on this (or perhaps I missed it), but I am keeping the circuits separate in my diagram. Would it be an issue to combine the neutral bus for AC Grid and Load? Lastly, this design keeps the inverter side separated as much as possible from the existing house wiring, connecting AC Grid and Load via the labeled connection interface in the diagram with the option to unplug things. This is part of my mobile power rack idea that I am still developing. I don't know what this interface will be yet... anyone here know what connectors I can use? The inverter has a 50A pass-through relay, so I guess it would need to handle at least that much. Thanks in advance for any feedback. The advice and information on this forum has been extremely helpful in designing this system. Quote Link to comment Share on other sites More sharing options...
Scorp007 Posted January 20, 2022 Share Posted January 20, 2022 No reply from any member???? Quote Link to comment Share on other sites More sharing options...
Yellow Measure Posted January 20, 2022 Share Posted January 20, 2022 Nice diagram. Looks good to go. Snuffleupagus 1 Quote Link to comment Share on other sites More sharing options...
Don Posted January 20, 2022 Share Posted January 20, 2022 On 2021/12/27 at 11:48 AM, Sir Rodgers said: Would it be an issue to combine the neutral bus for AC Grid and Load? Yes, keep the neutral for the essential load separate from the non-essentials. Snuffleupagus 1 Quote Link to comment Share on other sites More sharing options...
TonyH Posted January 20, 2022 Share Posted January 20, 2022 2 hours ago, Don said: Yes, keep the neutral for the essential load separate from the non-essentials. It is a legal requirement that you may not connect the inverter output neutral to the grid neutral. Snuffleupagus 1 Quote Link to comment Share on other sites More sharing options...
Leshen Posted January 21, 2022 Share Posted January 21, 2022 12 hours ago, TonyH said: It is a legal requirement that you may not connect the inverter output neutral to the grid neutral. It will just cause the earth leakage to trip. The neutrals have to be separated. Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 4 minutes ago, Leshen said: It will just cause the earth leakage to trip. The neutrals have to be separated. @Leshen Please explain, in my installation the neutral from the inverter is connected directly to the main DB neutral. Is this a problem ? so far the system is working fine and I don't have any issues with Earth Leakage trips. My system is connected as follows, from Mains via a double pole circuit breaker to the inverter AC supply. From the inverter AC output via a 63 Amp earth leakage back to the DB. please let me know if this is not correct. Quote Link to comment Share on other sites More sharing options...
Leshen Posted January 21, 2022 Share Posted January 21, 2022 13 minutes ago, Antonio de Sa said: @Leshen Please explain, in my installation the neutral from the inverter is connected directly to the main DB neutral. Is this a problem ? so far the system is working fine and I don't have any issues with Earth Leakage trips. My system is connected as follows, from Mains via a double pole circuit breaker to the inverter AC supply. From the inverter AC output via a 63 Amp earth leakage back to the DB. please let me know if this is not correct. If you open your DB, you will see that there are a minimum of 2 neutral bars, one neutral fed from the grid via the grid earth leakage, the other neutral via the essential earth leakage. On top of the breakers, will should have a copper busbar that's split with a live from the grid and a live from the inverter. Each of these live wires will have their own corresponding neutral which cannot be linked. Snuffleupagus, CobusK and Don 3 Quote Link to comment Share on other sites More sharing options...
Snuffleupagus Posted January 21, 2022 Author Share Posted January 21, 2022 (edited) Thanks for everyone's responses! Since I have posted this diagram I have received the following advice from various source, so consolidating it here: I was recommended to move the inverter AC grid input before the main RCD, not after as shown in the diagram. The reasoning being that power going back from the inverter to the main circuit should also go through the RCD to the rest of the circuits, and that inverters do not need to be on an RCD protected circuit themselves. As it is, the power fed back from the inverter bypasses main RCD protection. Downgrade the inverter CBs to 40A. This was due to having 6mm2 wiring, and a 63A breaker would need at least 16mm2. But apparently when you have a 40A breaker you can just barely get away with using 6mm2 wiring on that circuit. Move the changeover switch to the main db instead of the mobile "power station", so when the station is physically disconnected the essential load circuits can still be bypassed to the main grid. (This was an oversight on my part in the original planning.) Move the inverter input SPD after the inverter main switch, and optionally add an additional SPD on AC load if the circuit extends outside the house. This is indeed the case for me since I have the gate motor and outside lights on it... apparently lightning can cause pulses on any outside wiring which could feed back into the inverter. Not sure if it's overkill having 2 SPDs? But the explanation made sense. A bit pedantic but important nevertheless - the actual wiring for neutral needs to be black. (The diagram just uses blue to visually distinguish it from the DC wiring.) OK, so my question about connecting the neutrals has been answered. Thanks! Now all that's really left is to figure out how to connect the "power station" through an unpluggable interface. The largest sockets I found only carry 32A, but I would need something that can handle 40A at least... and there are 5 wires that need to be connected through whatever interface (AC grid L & N, and AC load L & N, and Earth). Edited January 21, 2022 by Sir Rodgers Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 5 minutes ago, Leshen said: If you open your DB, you will see that there are a minimum of 2 neutral bars, one neutral fed from the grid via the grid earth leakage, the other neutral via the essential earth leakage. On top of the breakers, will should have a copper busbar that's split with a live from the grid and a live from the inverter. Each of these live wires will have their own corresponding neutral which cannot be linked. @Leshen No, in my DB the mains ( life and neutral ) were connected to the main earth leakage incomer. the earth connected to the DB earth. From the output of the main earth leakage the neutral was connected the the DB only neutral bar and life connected Life to all the breaker in a chain configuration, there is only one neutral bar in my DB. Quote Link to comment Share on other sites More sharing options...
Leshen Posted January 21, 2022 Share Posted January 21, 2022 7 minutes ago, Antonio de Sa said: @Leshen No, in my DB the mains ( life and neutral ) were connected to the main earth leakage incomer. the earth connected to the DB earth. From the output of the main earth leakage the neutral was connected the the DB only neutral bar and life connected Life to all the breaker in a chain configuration, there is only one neutral bar in my DB. Please can you share a pic of your main DB. And do you perhaps have other DBs in the home. Also pics of the install Quote Link to comment Share on other sites More sharing options...
Don Posted January 21, 2022 Share Posted January 21, 2022 13 minutes ago, Antonio de Sa said: No, in my DB the mains ( life and neutral ) were connected to the main earth leakage incomer. I am not sure why we are still debating this? 1.) If you connect all the neutrals together, the earth leakage will most likely trip. 13 hours ago, TonyH said: It is a legal requirement that you may not connect the inverter output neutral to the grid neutral. 2.) It is against the law. Leshen 1 Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 40 minutes ago, Leshen said: Please can you share a pic of your main DB. And do you perhaps have other DBs in the home. Also pics of the install @Leshen Herewith how my DB was before the solar installation, please note my house is 40 years + old. Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 @Leshen This is how it's wired now. Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted January 21, 2022 Share Posted January 21, 2022 Hello. Can someone please indicate by way of a drawing how and where this Earth to neutral bridge is installed in my db board. I have a RCT VM3 and in the process of installing a RCT Max when I came across this piece of equipment and the explanation of its function. I only realized now with the mains (utility)switched off there is also no neutral connected in the db board. I assume you would connect it just below the Main isolator? I know what they say about assumption. Quote Link to comment Share on other sites More sharing options...
Leshen Posted January 21, 2022 Share Posted January 21, 2022 3 hours ago, Antonio de Sa said: @Leshen This is how it's wired now. Is there no way that you can take pictures of the actual DB as well as the installation? Quote Link to comment Share on other sites More sharing options...
Gnome Posted January 21, 2022 Share Posted January 21, 2022 4 hours ago, Antonio de Sa said: @Leshen Please explain, in my installation the neutral from the inverter is connected directly to the main DB neutral. Is this a problem ? so far the system is working fine and I don't have any issues with Earth Leakage trips. Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 8 minutes ago, Gnome said: @Gnome In my case the all hose in running on the inverters, so I think I'm OK Quote Link to comment Share on other sites More sharing options...
Gnome Posted January 21, 2022 Share Posted January 21, 2022 (edited) 31 minutes ago, Antonio de Sa said: @Gnome In my case the all hose in running on the inverters, so I think I'm OK Yeah but the point is, you can't bond the neutrals together. Else they wouldn't bother saying it needs to be split. Edited January 21, 2022 by Gnome Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 2 minutes ago, Gnome said: Yeah but the point is, you can't bond the neutrals together. Else they wouldn't bother saying it needs to be split. @Gnome That is if I had a split in my DB which is not the case, I have 2 X 5 KVA inverters = 10 KVA ample to feed my all house so there was not need to split circuits as essential non essential. Quote Link to comment Share on other sites More sharing options...
Leshen Posted January 21, 2022 Share Posted January 21, 2022 2 minutes ago, Gnome said: Yeah but the point is, you can't bind the neutrals together In all my installs, I have never seen the essential and non essential neutral bonded and everything work normally. Quote Link to comment Share on other sites More sharing options...
Deon Zeelie Posted January 21, 2022 Share Posted January 21, 2022 Just a remark on Leshen drawing. this is exactly what I am sitting with now. if the mains are opened there is no neutral connected as the isolator is double pole. This is why I am looking at the Earth to neutral bridge Quote Link to comment Share on other sites More sharing options...
Gnome Posted January 21, 2022 Share Posted January 21, 2022 (edited) 10 minutes ago, Antonio de Sa said: @Gnome That is if I had a split in my DB which is not the case, I have 2 X 5 KVA inverters = 10 KVA ample to feed my all house so there was not need to split circuits as essential non essential. But are you putting the inverter output neutral in that bar or your supplier neutral. That is the crux. It is perfectly fine having only 1 neutral bar that is fed from your inverter. But it read like what you described is, you only ran a line, neutral and return line between your inverter. And then rely on your supply neutral which you tied to your inverter neutral. Why anyone would think that is ok from a safety perspective, I don't know. Probably because they don't understand how electricity works. So I'm assuming you didn't actually do that instead still ran a line and neutral to your inverter and a line and neutral back from your inverter and are feeding your panel from the line and neutral coming back from the inverter Edited January 21, 2022 by Gnome Quote Link to comment Share on other sites More sharing options...
Gnome Posted January 21, 2022 Share Posted January 21, 2022 (edited) 11 minutes ago, Leshen said: In all my installs, I have never seen the essential and non essential neutral bonded and everything work normally. Yes they shouldn't be bonded. Your neutral from different power sources shouldn't be bonded. Note power sources. Doesn't matter if you term them essential or non-essential or whatever. What does matter is what the current source is. If one source is an inverter and battery bank and another source is a utility, their neutrals are not interchangeable and should be kept separate. 11 minutes ago, Leshen said: everything work normally. Just because a suicide plug works normally doesn't make it correct. I mean surely you can understand that? Just because you didn't die today driving without a seatbelt doesn't mean that it isn't stupid. See what I'm saying? Edited January 21, 2022 by Gnome CobusK 1 Quote Link to comment Share on other sites More sharing options...
Antonio de Sa Posted January 21, 2022 Share Posted January 21, 2022 5 minutes ago, Gnome said: But are you putting the inverter output neutral in that bar or your supplier neutral. That is the crux. It is perfectly fine having only 1 neutral bar that is fed from your inverter. But it read like what you described is, you only ran a line, neutral and return line between your inverter. And then rely on your supply neutral which you tied to your inverter neutral. Why anyone would think that is ok from a safety perspective, I don't know. Probably because they don't understand how electricity works. So I'm assuming you didn't actually do that instead still ran a line and neutral to your inverter and a line and neutral back from your inverter and are feeding your panel from the line and neutral coming back from the inverter @Gnome Ok understand what you say, so what must I do to rectify the problem. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.