In-Depth: Earthing and Bonding of Solar Inverters. Why?

[@narrowboatmlc]

Hi Roland - thanks so much - I found these videos really helpful for getting things straight in my mind - and interesting in their own right!

[@guy7gsa]

I can see why you were a pilot, so clam and composed.

[@RolandW_DIYEnergyandMore]

Flying is still easier then recording videos :)

[@guy7gsa]

😂😂😂

[@flinfaraday1821]

You say that you are turning the generator into a TN system by connecting the PE to ground rod. But how is the neutral bonded to earth by doing that? You still have to create the bond?

[@RolandW_DIYEnergyandMore]

Hi. Depending on the maker and model such gasoline generators can have one side of the generator winding connected to the chassis and that grounding screw. So, that would equal an inverter with an internal bond. You can find that out by measuring continuity towards the poles of the plugs with closed breaker on the device. If there is no continuity to any of the poles, then you would have to make an external N-G bond.

[@flinfaraday1821]

@@RolandW_DIYEnergyandMore Thanks!

[@topeye4202]

In a quite unlikely case you touch one leg at one appliance and the other leg on another defective tool or appliance, means you connect your self same as a normal consumer and if you sit or stand insulated enough against the ground (which is quite likely) no RCB will trip. Even if you stand or sit less insulated against the ground, the current that flows from one leg through you direct to the other leg is much higher (far more than 30mA), than the current that splits off and go to ground. That means even a TN-net isn't save too. Also in other case, when you are well grounded, sitting for example in a bath, there were cases the RCB didn't save life, cause RCB's dont limit the current, they just limiting the time, which can be not enough to prevent ventricular fibrillation and save life. But in this more likely case a IT-net will save life, cause no current will flow through anybody who touches just one conductor. If I compare this two more or less likely cases, the favour goes to IT-net I guess. I think earthing comes from a time where most apliances had a metall housing and melting fuses was the only possible protection. Today its quite unlikely you touch both wires at the same time, cause most things have insulated plastic housings.Also a big mains grid is impossible to keep floating, cause there will be several earthboundings anyway. But in a small household grid its possible. So why not use the advantage same as some laboratories have installed a insolation transformer for savety reasons ? Did I made any missconceptions?

[@RolandW_DIYEnergyandMore]

No, no missconceptions. The IT system is discussed in one of the subsequent videos. I am just recommending to follow International Electrical Commission Rules which for IT system states 2 risks when you are not using it as per its advantages where you create a safe bubble as you mention. A housing installation with many electrical circuits will inevitably have a risk that somewhere one day you will have a "first insulation fault" which will turn the IT system into a TN system. The problem is that if you are not aware of it, then you might easily get into a situation where you didn't expect a shock. Therefor IT systems typically will be monitored by a "Bender" device = insulation monitoring device. The other risk is high voltage surges in IT systems. The risk of those will increase as well if you increase the size of your IT installation and expand it to a whole house. Its your decision which way you go. Just always be aware about the risks which any of the 5 different earthing arrangements bring with them.

[@topeye4202]

@@RolandW_DIYEnergyandMore Thank you for your competent and liberal answer. I will apply same savety rules in a IT-net as in a TN-net, not touching anything without testing at least with a previously in known conditions tested test pen, so the risk of a unexpected shock is minimized. I have learned my lesson decades ago, when i was standing in mud with wet espadrilles and touched a hot wire with a big uninsulated plier. I have allready installed a RCB weeks ago on the output, just in case I come to the conclusion to add a bridge between N and Ground will be smart....I am still undecided......

[@ranarizwanahmed]

Which metal is best for earthing (PE)? Iron rod or copper rod? You expert advice shall be highly appreciated

[@RolandW_DIYEnergyandMore]

you can buy what is available to you. i would go gor a copper rod as iron rods will corrode much faster and will have to be replaced at some point.

[@ucheeze6220]

Stainless steel is generally regarded as best, followed by copper-bonded steel, especially where strength is important as well as longevity.

[@med687]

Hello Roland, thank you for your great work, I’ve learned so much from you, my question is; I’ve an EASUN off grid 5000 watts, 48 volts inverter and when I use my multimeter to test continuity from ground to neutral, there is, so that means it’s already bonded I would like to use it completely off grid, so how do I wire it please? Thank you once again

[@RolandW_DIYEnergyandMore]

Hi. If it is bonded and your plan is to use it purely off-grid, than this is easy. You just connect you circuit or a distribution directly to the inverter terminals as by their purpose. You can follow the instructions given in the "simple off-grid" video, just without putting a N-G bond inside the distribution unit.

[@med687]

Thank you Roland, one more question about earth rod, do i need one?

[@RolandW_DIYEnergyandMore]

@@med687 that depends on your installation. if you want an earthed system or isolated, only run a load from the inverter directly or connect many circuits. if you are planning to connect a sort of house installation and want human protection by RCD/GFCI then you need a rod.

[@med687]

Ok thank you for all your help and advice, I really appreciate it, have a great day

[@seamusleddy2933]

Hi to all, i have bought a solar inverter with a grid/generator battery charging function and it has 2 inputs one for (SOLAR PV IN)and the second is (AC IN GRID OR GENERATOR) this connection has 3 terminals Live - Earth - Neutral beside this connection is an AC out connection only 2 terminals Live-Neutral there is a separate PE connection on the inverter casing would this system be (IT) ? if yes how can i connect safely to my Distribution panel ? if my (GRID IN) connection provides my inverter with a GROUND/EARTH wire is my (AC OUT) safe to connect back into the distribution panel ? Many thanks

[@RolandW_DIYEnergyandMore]

Well, that's about the question I started with and now 15 Videos and hours of footage later I am still not done. Every power source by its nature is IT. Ground/Earth can only be provided by a Ground source. It's the Grid we will typically find as a grounded power source, because it is delivered to us like that. But with inverters, gas generators, etc which you buy and bring to your home, you need to decide what sort of Earthing system you want to use, if any... So, knowing how an inverter/grid input/house installation will behave depends on many factors. The most important one is the type of earthing system your grid comes with. And then what exactly you want to do with the AC-In. AC-In is a broad description. There is a complex system hiding behind those 3 pins as you will find out in my next video this weekend. From your description of your inverter, I know that you have bought yourself a device that promises to serve any of your needs. But those claims manufacturers make are very easy. In reality there are so many details to consider and you will see that a deeper dive into this topic will open a chest of questions which you will have to find your individual answers to. I think this channel is a good start. Every video in the Inverter grounding /earthing playlist tackles several new questions and will finally give you a broad understanding of what this fuss is about. Thanks for watching, good luck on your quest to a happy PV-Life!

[@seamusleddy2933]

@@RolandW_DIYEnergyandMore Thank you Roland for the reply i am realistic and i know that the solar inverter i purchased will have its limits i do not wish to run all my appliances using this inverter, i would like to use it for lighting and some small cooking appliances for all bigger appliances i will switch to the grid, my reason for watching all your videos on this topic is to ensure that any appliances i connect to my solar inverter are safe to use and grounded/earthed correctly , i look forward to your next video , Many thanks from Ireland

[@gimiandtarascott8496]

so In a fully off grid system, with a hybrid inverter. I have bonded the neutral to ground (between the ac output on the inverter and rcd input in the main consumer unit).The earth/ground bus is connected to a ground rod . Now if I want to add a generator (HYUNDAI 6600 SE-LR DIESEL) to my utility AC input on the hybrid inverter (EPEVER 5000 upower hi series). How do i connect this to the input. Do i still add a ground rod to the generator PE. What about if the generator also has a bonded earth neutral? will this not introduce a second earth neutral bond. one at the generator and one at the main consumer panel as described earlier?

[@RolandW_DIYEnergyandMore]

hi, you connect L and N to the AC input of the inverter, and connect the generators PE to the PE bar at your load center. Use a common rod for both grounds. even if N is bonded at 2 places, that is no problem as you are off-grid. Bonding just provides a return path to the active Neutral and keeps all Neutrals at Zero potential. it is just important to do all bonding before the RCD. on generator and inverter side use double pole breakers to protect from short circuits only and keep the installation safe from human interference :)

[@gimiandtarascott8496]

Problem is, I cannot see from the documentation if the Hyundai generator is bonded. The inverter documentation doesn't mention bonding anywhere. Although it says utility input can be used with a generator

[@RolandW_DIYEnergyandMore]

@@gimiandtarascott8496 you can use a multimeter in resistance mode and measure between earting screw and L and N of a socket. no resistance to one of the pins (N) means means there is a bond. You can as well run the generator and measure voltage between earth and L and N. if there is voltage on N, there is no bond.

[@gimiandtarascott8496]

@@RolandW_DIYEnergyandMore ok tested it. so on the generator there is continuity between N to ground pin. L to ground pin, N to chassis ground. Live to chassis ground. So it is bonded it seems. Now if the load center is bonded before rcd and after inverter output. I am not sure how to resolve this. should I still connect the earth/ground wire from generator cable to the load center ground bar (common ground). ultimately I am aiming to trigger the ATS automatic start on generator when inverter activates the dry contact when batteries are low. So i want to avoid any manual transfer switches.

[@RolandW_DIYEnergyandMore]

@@gimiandtarascott8496 i would still bond at load panel and use common ground with to bonds. its all about having a return path for fault current to each of the 2 sources of power. there is no grid involved.

[@closertothetruth9209]

nice one

[@jonerasmus9399]

I wish you showed how and where the neutral and ground is bonded . 5 stars for explanation but 7 stars for demonstrating

[@RolandW_DIYEnergyandMore]

Hi. That depends on what you are trying to achieve. If you want to use a generator as an off-grid power source, then you can just follow the instructions from the "Simple Off-Grid System" video. If you are using a generator as the alternate AC input from a PV-Inverter, then you will have to study such hybrid systems.

[@jonerasmus9399]

@@RolandW_DIYEnergyandMore I would like to wire a generator into my home for emergency back up and id like to know how and where to connect the n to earth . I do plan on using a change over switch

[@RolandW_DIYEnergyandMore]

@@jonerasmus9399 when the Grid is involved, then you need to know the earthing system of the grid and if it comes with a N-G bond at your property. Then it depends where this bond is done. Is it accessible or not? If it is accessible then you can use the original grid input at one side of the transfer switch and the generator L, N at the other side. The new N-G bond is then in your panel after the transfer switch output. If the grid N-G bond is inaccessible to you then you need to use that as ATS Input as it is and as well make a N-G bond at the generator input side of ATS. No more bonding after the transfer switch! There can only be one active bond. If you have a TT-Grid, then the bond can only be at generator ATS input. There shall not be a bond when the Grid is the active power source. Maybe the video about practical guidance can give you some ideas. You see, there is no simple answer or a standard diagram which explains all. That is why this playlist has 12 videos :)

[@jonerasmus9399]

@@RolandW_DIYEnergyandMore Thank you for taking the time, i appreciate all the effort you put into this topic . Wish my lecturers at college put in the effort you did to explain the depth that earthing actually requires . I'm a new electrician and i find myself learning about earthing all over again.

[@offgridwanabe]

Can you tell us more about 2 ground sources in one system?

[@RolandW_DIYEnergyandMore]

ok. I will draw up a few options how to tackle those sort of systems

[@tranerekt1731]

Why? Because if you don't, lightning will fry your $1600 inverter/charger like it did to mine.

[@RolandW_DIYEnergyandMore]

Yes absolutely. But a lucky guy could avoid lightning damage if he had installed SPDs, and still electrocute himself because the inverter is not integrated into an Earthing system :) That's why it is still important to keep this two very important issues separate. Thanks for the comment!

[@tranerekt1731]

@@RolandW_DIYEnergyandMoreyes, SPD might've helped a SMART man. I didn't have ANY earthing yet when it happened. Now I have bare #8 copper attached the panels, the inverters, the AC chargers, the charge controllers and the generator, and then to an 8 foot rod in the ground. Then I have an extension cord running from my inverter/charger/battery box to my trailer's 30 amp plug. Am I good?

[@adairjanney7109]

Nothing is greener than oil, you think you can make all this crap without OIL? You are just going to have to remake it and remake it and remake it what its supposed to last 25 years yeah right, you are actually far less green running the stuff you do. You want to be green? Then go back to the stone age